Identification of electrode combination for efficacious electrical stimulation therapy

ABSTRACT

One or more efficacious electrode combinations for delivering electrical stimulation therapy to a patient may be selected based on the delivery of electrical stimulation to the patient via a predefined set of test electrode combinations in a predetermined order. In some examples, the electrode combinations of the set are arranged in the predetermined order such that adjacent electrode combinations in the order include at least one shared anode electrode or cathode electrode. In addition, the electrode combinations in the predetermined order may define a predetermined sequence of electrode patterns, each electrode pattern defining a relative arrangement between one or more anodes and one or more cathodes of the respective electrode pattern. In some examples, the transition between electrode combinations in the predefined set is achieved by incrementally adjusting at least one of anodic amplitudes assigned to active anode electrodes or cathodic amplitudes assigned to active cathode electrodes.

TECHNICAL FIELD

The disclosure relates to therapy delivery by a medical device and, moreparticularly, delivery of electrical stimulation therapy.

BACKGROUND

Medical devices, such as electrical stimulators, may be used indifferent therapeutic applications, such as deep brain stimulation(DBS), spinal cord stimulation (SCS), pelvic stimulation, gastricstimulation, peripheral nerve stimulation, functional electricalstimulation. A medical device may be configured to deliver therapy to apatient to treat a variety of symptoms or patient conditions such aschronic pain, tremor, Parkinson's disease, other types of movementdisorders, seizure disorders (e.g., epilepsy), urinary or fecalincontinence, sexual dysfunction, obesity, mood disorders, gastroparesisor diabetes. In some therapy systems, an

or external electrical stimulator delivers electrical therapy to atarget tissue site within a patient with the aid of one or moreelectrodes, which may be deployed by medical leads.

During a programming session, a clinician may select one or more therapyprograms (which may also referred to as therapy parameter sets) thatprovide efficacious therapy to the patient, where each therapy programmay define values for a set of therapy parameters. A medical device maydeliver therapy to a patient according to one or more stored therapyprograms. In the case of electrical stimulation, the therapy parametersmay define characteristics of the electrical stimulation waveform to bedelivered and the electrode combination with which the electricalstimulation is delivered. In examples in which electrical stimulation isdelivered in the form of electrical pulses, for example, the therapyparameters may include an electrode combination, an amplitude, which maybe a current or voltage amplitude, a pulse width, and a pulse rate.

SUMMARY

The disclosure describes devices, systems, and techniques foridentifying one or more electrode combinations for delivering electricalstimulation therapy to a patient. In some examples, electrodecombinations of a predefined set of electrode combinations areautomatically tested for delivery of electrical stimulation therapy to apatient in a predetermined order, where the electrode combinations arearranged in the predetermined order such that adjacent electrodecombinations in the order include at least one shared anode electrode orcathode electrode. In addition, in some examples, the electrodecombinations of the set are arranged in the predetermined order suchthat electrode combinations propagate down the lead (e.g., from aproximal end of the lead to a distal end of the lead or vice versa) aselectrode combinations are tested in the predetermined order.

In some examples, the set of electrode combinations tested in thepredetermined order define a predetermined sequence of electrodepatterns, each electrode pattern defining a relative arrangement betweenone or more anodes and one or more cathodes of the respective electrodepattern. An electrode combination may be defined by a subset ofelectrodes of a lead with which electrical stimulation is delivered tothe patient, and the polarities of the particular electrodes. Thus, theelectrode combination may be defined by a subset of electrodes of alead, respective electrode polarities, and an electrode pattern.

In some examples, the electrode patterns are selected such that theanode and cathode electrodes of every electrode combination in thepredefined set are programmed together on adjacent electrodes withoutany inactive (also referred to as “off” or “unused”) electrodes betweenthe active electrodes. This type of arrangement of anode and cathodeelectrodes may minimize the area of activation of the neurons as theelectrode combinations propagate down the electrode array, and providemore precise electrical stimulation.

In some examples, at least one electrode pattern may appear multipletimes at different positions in the predetermined sequence. For example,the predetermined sequence may include a repeating sequence of electrodepatterns. The sequence of electrode patterns may be repeated as, forexample, electrode combinations are propagated down a lead.

In some examples, the amplitudes assigned to the anode and cathodeelectrodes of test electrode combinations, referred to herein as anodicamplitudes and cathodic amplitudes, respectively, are adjusted in apredetermined manner as the electrode combinations of the predefined setare tested in the predetermined order. The predetermined manner may beselected such that one or more electrode combinations of the predefinedset are delivered with different combinations of anodic and cathodicamplitudes. For example, the anodic amplitude and/or cathodic amplitudesmay be incrementally modified (e.g., increased or decreased) in thepredetermined manner, according to a predefined schedule, during theautomatic delivery of electrical stimulation via the predefined set ofelectrode combinations. For a particular electrode combination, theefficacy of therapy may change depending on the anodic amplitude,cathodic amplitude, or both, of each of the active anodes and cathodes,respectively. Thus, automatically adjusting the anodic amplitude and/orcathodic amplitudes in a predetermined manner may help thoroughly testone or more electrode combinations in an efficient manner.

In addition, the incremental modification to the anodic amplitude and/orcathodic amplitude may result in transitions between electrodecombinations that may minimize discomfort to the patient and minimize,if not eliminate, user input required to manually adjust the amplitudes.

In one aspect, the disclosure is directed to a method comprising, withone or more processors, selecting a predefined set of electrodecombinations, and, with the one or more processors, controlling amedical device to deliver electrical stimulation to a patient via thepredefined set of electrode combinations in a predetermined order. Theelectrode combinations are arranged in the predetermined order such thatadjacent electrode combinations in the order include at least one sharedanode electrode or cathode electrode. In addition, the electrodecombinations in the predetermined order define a predetermined sequenceof electrode patterns, each electrode pattern defining a relativearrangement between one or more anodes and one or more cathodes of therespective electrode pattern, where at least one electrode patternappears multiple times at different positions in the sequence.

In another aspect, the disclosure is directed to a system comprising amedical device and a processor configured to control the medical deviceto deliver electrical stimulation to a patient via a predefined set ofelectrode combinations in a predetermined order. The electrodecombinations are arranged in the predetermined order such that adjacentelectrode combinations in the order include at least one shared anodeelectrode or cathode electrode. In addition, the electrode combinationsin the predetermined order define a predetermined sequence of electrodepatterns, each electrode pattern defining a relative arrangement betweenone or more anodes and one or more cathodes of the respective electrodepattern, where at least one electrode pattern appears multiple times atdifferent positions in the sequence.

In another aspect, the disclosure is directed to a system comprisingmeans for delivering electrical stimulation to a patient, and means forcontrolling the means for delivering electrical stimulation to deliverelectrical stimulation to the patient via a predefined set of electrodecombinations in a predetermined order. The electrode combinations arearranged in the predetermined order such that adjacent electrodecombinations in the order include at least one shared anode electrode orcathode electrode. In addition, the electrode combinations in thepredetermined order define a predetermined sequence of electrodepatterns, each electrode pattern defining a relative arrangement betweenone or more anodes and one or more cathodes of the respective electrodepattern, where at least one electrode pattern appears multiple times atdifferent positions in the sequence.

In another aspect, the disclosure is directed to a computer-readablestorage medium comprising instructions. The instructions cause aprogrammable processor to control a medical device to deliver electricalstimulation to the patient via a predefined set of electrodecombinations in a predetermined order and select an electrodecombination from the predefined set based on the delivery of theelectrical stimulation by the medical device. The electrode combinationsare arranged in the predetermined order such that adjacent electrodecombinations in the order include at least one shared anode electrode orcathode electrode. In addition, the electrode combinations in thepredetermined order define a predetermined sequence of electrodepatterns, each electrode pattern defining a relative arrangement betweenone or more anodes and one or more cathodes of the respective electrodepattern. At least one electrode pattern appears multiple times atdifferent positions in the sequence.

In another aspect, the disclosure is directed to a computer-readablestorage medium, which may be an article of manufacture. Thecomputer-readable storage medium includes computer-readable instructionsfor execution by a processor. The instructions cause a programmableprocessor to perform any part of the techniques described herein. Theinstructions may be, for example, software instructions, such as thoseused to define a software or computer program. The software or computerprogram may be, for example, modified or otherwise updated base on aspecific patient's requirements.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating an example system including amedical device, electrical stimulation leads, and a medical deviceprogrammer.

FIG. 2 is functional block diagram illustrating components of an examplemedical device.

FIG. 3 is a functional block diagram illustrating components of anexample medical device programmer.

FIGS. 4A and 4B are flowcharts illustrating example techniques foridentifying one or more electrode combinations that may provideefficacious therapy for a patient.

FIGS. 5A-5D are schematic diagrams illustrating an example group ofelectrode patterns present in a predefined set of electrodecombinations.

FIGS. 6-9 are tables illustrating example sets of test electrodecombinations that may be used to identify one or more efficaciouselectrode combinations for a patient.

FIGS. 10A-10D illustrate an example predefined schedule of amplitudeadjustments, which includes an example set of test electrodecombinations and corresponding anodic and cathodic amplitudes.

FIGS. 11A-11D illustrate another example predefined schedule ofamplitude adjustments.

FIG. 12 is a schematic diagram illustrating an example graphical userinterface (GUI) that may be generated and displayed by a programmer.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram illustrating an example system 10, whichis configured to deliver electrical stimulation therapy to patient 12,who is ordinarily a human patient. System 10 includes implantablemedical device (IMD) 14 and electrical stimulation leads 16A, 16B(collectively referred to as “electrical stimulation leads 16” or “leads16”), and external programmer 18. Although the techniques described inthis disclosure may be generally applicable to a variety of medicaldevices including external and implantable medical devices, applicationof such techniques to implantable medical devices and, moreparticularly, implantable electrical stimulators (e.g.,neurostimulators) will be described for purposes of illustration. Moreparticularly, the disclosure will refer to an implantable spinal cordstimulation (SCS) system for purposes of illustration, but withoutlimitation as to other types of medical devices and target therapydelivery sites. For example, in other examples, instead of, or inaddition to IMD 14, system 10 may include an external medical device(e.g., an external electrical stimulator) that is not implanted in thepatient's body, and percutaneously implanted leads or external leads.

IMD 14 is configured to generate and deliver electrical stimulationtherapy to patient 12. IMD 14 may include a biocompatible outer housing,such as titanium or stainless steel, or a polymeric material such assilicone or polyurethane. In examples in which IMD 14 is implanted inpatient 12, IMD 14 may be implanted at any suitable location withinpatient 12.

In the example of FIG. 1, IMD 14 is an implantable electrical stimulatorconfigured for SCS, e.g., for relief of chronic pain or other symptoms.Stimulation energy is delivered from IMD 14 to spinal cord 20 of patient12 via one or more electrodes of implantable leads 16. In someapplications, such as SCS, leads 16 may be implanted in patient 12 suchthat longitudinal axes of leads 16 (e.g., extending from a proximal endto a distal end of the respective lead) are substantially parallel toone another. However, other relative arrangements of lead 16 may also beused and may differ depending on the target tissue site for theelectrical stimulation therapy. In addition, although two leads 16 areshown in the example shown in FIG. 1, in other examples, system 10 mayinclude any suitable number of leads, such as one lead, three leads, ormore than three leads. In addition, in some examples, system 10 mayinclude a leadless electrical stimulator, as discussed in further detailbelow,

Although SCS therapy is primarily referred to throughout the descriptionof FIG. 1, system 10 may be configured to deliver electrical stimulationtherapy to patient 12 for any patient condition that may benefit fromstimulation therapy. For example, system 10 may be configured to deliverelectrical stimulation therapy for treatment of movement disorders orother neurodegenerative impairment, whether by disease or trauma (e.g.,disorders with one or more symptoms that affect muscle control andmovement problems, such as rigidity, bradykinesia, rhythmichyperkinesia, nonrhythmic hyperkinesia or akinesia). As another example,system 10 may be configured to deliver electrical stimulation therapyfor treatment of Parkinson's disease, seizure disorder (e.g., epilepsy),urinary or fecal incontinence, sexual dysfunction, obesity,gastroparesis, psychiatric disorders (e.g., depression, mania, obsessivecompulsive disorder, anxiety disorders, and the like), musclestimulation (e.g., functional electrical stimulation (FES) of muscles)or obesity. In this manner, in some examples, system 10 may beconfigured to provide therapy taking the form of any one or more of deepbrain stimulation (DBS), peripheral nerve stimulation (PNS), peripheralnerve field stimulation (PNFS), DBS, cortical stimulation (CS), pelvicfloor stimulation, gastric stimulation, or any other electricalstimulation therapy.

Leads 16 may be implanted within patient 12 and directly or indirectly(e.g., via a lead extension) electrically connected to IMD 14. Asmentioned above, in some other examples, leads 16 may be implanted andcoupled to an external stimulator, e.g., through a percutaneous port.The external stimulator may be, for example, a trial or screeningstimulation that is used on a temporary basis to evaluate potentialefficacy to aid in consideration of chronic implantation for patient 12.In other examples, IMD 14 is a leadless stimulator with one or morearrays of electrodes arranged on a housing of the stimulator in additionto, or instead of, leads 16 that extend from the outer housing of IMD14.

Leads 16 each include a plurality of electrodes (not shown in FIG. 1)disposed proximate to a distal end of the respective lead and/or atother positions at intermediate points along the lead. Electrodes ofleads 16 are configured to deliver electrical stimulation generated byIMD 14 to a target tissue site of patient 12. A selected subset of theelectrodes located on leads 16 and the polarities of the electrodes ofthe subset collectively define an “electrode combination.” An electrodecombination refers to the combination of single or multiple cathodeelectrodes and single or multiple anode electrodes with which IMD 14delivers electrical stimulation signals to patient 12. Stimulationcurrent generated by IMD 14 flows between the cathodes and anodes fordelivery of electrical therapy. For example, electrons may flow from theone or more electrodes acting as anodes for an electrode combination tothe one or more electrodes acting as cathodes for the combination. Thecurrent between cathodes and anodes may stimulate neurons between andproximate to the anodes and the cathodes.

The electrodes of leads 16 may be electrode pads on a paddle lead,circular (e.g., ring) electrodes surrounding the body of the respectivelead 16A or 16B, conformable electrodes, cuff electrodes, segmentedelectrodes, or any other type of electrodes capable of forming unipolar,bipolar or multipolar electrode combinations for therapy. In general,ring electrodes arranged at different axial positions at the distal endsof leads 16 will be described for purposes of illustration.

Leads 16 may be percutaneously or surgically implanted in patient 12 ona temporary or permanent basis such that at least one electrode ispositioned proximate to a target tissue site, which may be any tissueaffected by electrical stimulation energy. The target tissue site maybe, for example, a nerve or other tissue site, such as a spinal cord 20in the example shown in FIG. 1 (e.g., within an intrathecal space orepidural space of spinal cord 20, or, in some examples, adjacent nervesthat branch off of spinal cord 20), a pelvic nerve, a pudendal nerve, astomach, a bladder, or a brain or other organ of a patient, or a muscleor muscle group of a patient.

In the example shown in FIG. 1, leads 16 may be introduced into spinalcord 20 via any suitable region, such as the thoracic, cervical orlumbar regions. Stimulation of spinal cord 20 may, for example, preventpain signals from traveling through spinal cord 20 and to the brain ofpatient 12. Patient 12 may perceive the interruption of pain signals asa reduction in pain and, therefore, efficacious therapy results.

The deployment of electrodes via leads 16 connected to IMD 14 isdescribed for purposes of illustration; an array of electrodes may alsobe deployed in different ways. For example, a housing associated with aleadless stimulator may carry an array of electrodes, e.g., electrodesarranged to define a plurality of rows and/or columns (or otherpatterns). Such electrodes may be arranged as surface electrodes, ringelectrodes, or protrusions. As another example, an electrode array maybe formed by rows and/or columns of electrodes on one or more paddleleads. In some examples, electrode arrays may include electrodesegments, which may be arranged at respective positions around aperiphery of a lead, e.g., arranged in the form of one or more segmentedrings around an outer perimeter of a cylindrical lead. The techniquesdescribed herein for identifying one or more efficacious electrodecombinations may be used with any array of electrodes.

IMD 14 is configured to generate and deliver electrical stimulationtherapy to patient 12 according to a therapy program, which may also bereferred to as a set of electrical stimulation parameter values.Delivery of stimulation pulses will be described for purposes ofillustration. However, electrical stimulation may be delivered in otherforms, such as continuous waveforms. The electrical stimulation may bedelivered as controlled voltage pulses or waveforms, or as controlledcurrent pulses or waveforms.

A therapy program defines values for one or more electrical stimulationparameter parameters that define an aspect of the therapy delivered byIMD 14 according to that program. The electrical stimulation parametersmay include an electrode combination, voltage or current amplitude of anelectrical stimulation signal, a frequency of the electrical stimulationsignal, and, in the case of electrical stimulation pulses, pulse rate,pulse width, and other appropriate parameters such as duration or dutycycle. The electrode combination may determine the target tissue sitefor the electrical stimulation energy, and, therefore, whichphysiological effects are perceived by patient 12. The intensity and theextent of those effects may be a function of the stimulation rate, pulsewidth, voltage or current amplitude, or any combination thereof.

In some examples, system 10 stores a plurality of therapy programs(e.g., in a memory of IMD 14, programmer 18 or another device), and IMD14 is configured to generate and deliver electrical stimulation therapyto patient 12 in accordance with one or more stored therapy programs. Insome examples, IMD 14 delivers therapy to patient 12 according tomultiple programs, wherein multiple programs are contained within eachof a plurality of groups. For example, each program group may support analternative therapy selectable by patient 12, and IMD 14 may delivertherapy according to the multiple programs by, e.g., rotating throughthe multiple programs of the group when delivering stimulation such thatnumerous conditions of patient 12 are treated.

The process of selecting values for the electrical stimulationparameters that provide efficacious results for a particular patient 12can be time consuming, and may require a great deal of trial and errorbefore a “best” set of therapy parameter values is determined. The“best” set of therapy parameter values may be a set of therapy parametervalues that is better than other sets of therapy parameter values testedin terms of clinical efficacy (e.g., symptom relief, coverage area)versus side effects experienced, and, in some cases, based on medicaldevice performance characteristics (e.g., power consumption). During aprogramming session (or at another time), a clinician may selectivelytest a relatively large number of electrode combinations in order toidentify an efficacious electrode combination. A programming session mayoccur during implant of IMD 14, during a trial session, during anin-clinic or remote follow-up session after IMD 14 is implanted orotherwise provided to patient 14, or at another time, The process ofselecting electrode combinations, e.g., selecting electrodes of leads 16and the polarities of the electrodes, can be particularly time-consumingand tedious due to the relatively large number of electrode combinationsthat may be possible from electrodes of leads 16.

During a programming session (or at another time), a clinician may testa plurality of different electrode combinations on patient 12 toidentify one or more efficacious electrode combinations, which may thenbe selected for further testing on patient 12 or for chronic therapydelivery to patient 12, and/or may be used to find additionalefficacious electrode combinations. For example, the clinician maycontrol IMD 14 (e.g., via programmer 18) to deliver test (or “trial”)electrical stimulation to patient via each of the electrode combinationsof the plurality for a respective test period, determine the efficacy oftherapy delivered via each of the tested electrode combinations, andselect one or more electrode combinations based on the determinedefficacy of the tested electrode combinations. The plurality ofelectrical combinations may tested in real time, e.g., at theclinician's office, during one programming session.

In some existing techniques, a clinician may test electrode combinationsby manually specifying each electrode combination to test based onintuition or some idiosyncratic methodology, and recording notes on theefficacy and side effects of each electrode combination after deliveryof stimulation via that electrode combination. The clinician may thenlater compare and select from the tested electrode combinations. As anexample illustrating the magnitude of such a task, if two leads 16include eight electrodes each, then over forty-two million potentialelectrode combinations are available for testing on patient 12 in orderto identify an efficacious electrode combination. While the existingtechniques for selecting one or more efficacious electrode combinationsmay be useful, the existing techniques may also be relatively timeconsuming. In addition, a lack of a systematic technique for testingdifferent electrode combinations may leave the clinician or patient 12with a lack of confidence in the selected one or more electrodecombinations, e.g., because of a feeling that the “best” electrodecombination was not identified.

Devices, systems, and techniques for efficiently identifying one or moreelectrode combinations for delivering efficacious electrical stimulationtherapy to a patient are described herein. The devices, systems, andtechniques described herein may enable a clinician or patient 12 to morequickly identify efficacious electrode combinations with which IMD 14may deliver electrical stimulation therapy to patient 12 compared to thetechniques in which a clinician manually selects each test electrodecombination.

For ease of description, the techniques are primarily described as beingemployed by programmer 18. In other examples, the techniques may beimplemented by any suitable device, such as IMD 14 or another computingdevice (e.g., a remote computing device such as a cloud computingdevice), alone or in combination with programmer 18. In addition, forease of description, the techniques are primarily described as beingemployed to select one or more electrode combinations that include acolumn of electrodes of only lead 16A. In other examples, the techniquesmay be implemented to select more electrode combinations that includeelectrodes of only lead 16B, electrodes of both leads 16, and electrodesof a lead including a plurality of columns of electrodes (e.g., a leadincluding segmented electrodes or a multi-column paddle lead).

In the example shown in FIG. 1, programmer 18 is configured toautomatically control IMD 14 to deliver electrical stimulation topatient 12 via each electrode combination of a predefined set ofelectrode combinations in a predetermined order, and one or moreefficacious electrode combinations with which IMD 14 may deliverelectrical stimulation therapy to patient 12 can be selected based onthe electrical stimulation. For example, programmer 18 may store thepredefined set of a plurality of different electrode combinations, andmay be configured to automatically select electrode combinations fromthe set (e.g., with no user intervention selecting electrodecombinations) to test on patient 12 in a predetermined order (e.g., anonrandom order). In this way, programmer 18 may be configured tocontrol IMD 14 to automatically scan through each of the electrodecombinations in the predefined set.

In some examples, programmer 18 is configured to automatically scanthrough each of the electrode combination in the predefined set withlimited user interaction. For example, programmer 18 can be configuredto start the automatic testing of a predefined set of electrodecombinations in response to user input requesting a start the automaticscanning, and to stop the automatic testing in response to user inputrequesting a stop the automatic scanning. After the scan is started inresponse to user input, programmer 18 may be configured to automatically(e.g., without user input) select electrode combinations from thepredefined set in a predetermined order, and control IMD 14 to deliverelectrical stimulation according to the selected electrode combinationsin the predetermined order. In contrast to systems in which userinteraction is required during a programming session to select electrodecombinations to test (e.g., to select a next electrode combination totest after testing a currently selected electrode combination) onpatient 12, programmer 18 may be configured to save time and reduce theburden for the user to test a plurality of electrode combinations onpatient 12.

In some examples, the electrode combinations of the predefined set maybe selected and stored as part of the set prior to initiating the scan(also referred to herein as a propagation) through the electrodecombinations of the predefined set. Accordingly, in some examples, aclinician may know which electrode combinations are going to be testedon patient 12 prior to initiating the scan through the electrodecombinations of the predefined set. Because IMD 14 delivers theelectrical stimulation to identify an efficacious electrode combination,the electrical stimulation delivered during the scanning through the setof electrode combinations may be referred to as “trial” or “test”electrical stimulation. The one or more electrode combinations selectedfrom the set may be used for one or more purposes, such as for furthertesting on patient 12, generation of one or more therapy programs usedfor therapy delivery by IMD 14, or for identification of additionalelectrode combinations to test on patient 12.

In some examples, once the testing of a predefined set of test electrodecombinations is initiated, programmer 18 can automatically select thetest electrode combinations from the set based on the predeterminedorder, and control IMD 14 to deliver electrical stimulation via eachselected test electrode combination without user intervention, e.g.,user input selecting specific electrode combinations to test orindicating a direction in which the electrical stimulation should beshifted. In this way, programmer 18 can be configured to execute anauto-scan of a plurality of electrode combinations on patient 12 thatcan be run independently of any user control. This may help minimize theamount of clinician knowledge, experience, skill, or any combinationthereof, required to identify an efficacious electrode combination forpatient 12. Delivery of electrical stimulation by IMD 14 may, but neednot be, stopped between test electrode combinations of the set for userparameter adjustments, e.g., to increase or decrease the amplitude ofthe electrical stimulation.

The predetermined order of the electrode combinations of the set isselected such that the transitions between electrode combinations arelogical and efficient, e.g., selected to reduce the amount of timeconsumed for the transitions. For example, in some examples, theelectrode combinations are arranged in the predetermined order such thateach electrode combination includes at least one anode or cathode from apreceding electrode combination in the predetermined order. That is, theelectrode combinations of the set tested on patient 12 may be arrangedin the predetermined order such that adjacent electrode combinations inthe order include at least one shared anode electrode or cathodeelectrode, such as at least one shared anode electrode and at least oneshared cathode electrode. This arrangement may help increase the speedwith which the plurality of electrode combinations are tested on patient12, e.g., by reducing the amount of time consumed to increase ordecrease the intensity of electrical stimulation delivered via aparticular electrode during a transition between electrode combinations.This arrangement of electrode combinations may also help a user (e.g.,patient 12 or a clinician) better comprehend the manner in which theelectrode combinations are being tested.

An arrangement in which at least some of the adjacent electrodecombinations of the set include at least one shared anode electrode andat least one shared cathode electrode, the impact from incrementalchanges in anodic amplitude, cathodic amplitude, or both, may beminimized, e.g., when transitioning between electrode combinations. Inaddition, the arrangement in which at least some of the adjacentelectrode combinations of the set include at least one shared anodeelectrode and at least one shared cathode electrode may help minimizethe likelihood that overstimulation will occur suddenly from one step toanother.

In some examples, at least some of the electrode combinations are testedat a plurality of different anodic and cathodic amplitude combinations.For a particular electrode combination, IMD 14 may assign each anode inthe electrode combination an anodic amplitude and assign each cathode inthe combination a cathodic amplitude, and control the sourcing andsinking of electrical stimulation via the anode and cathode electrodesin accordance with the assigned anodic and cathodic amplitudes in orderto deliver electrical stimulation to patient 12 via the electrodecombination. An anodic or cathodic amplitude may be, for example,defined as a portion of the total current or charge delivered by theelectrode, displayed as a percentage contribution or effective amplitudeof the electrode.

In some example techniques for testing a predefined set of electrodecombinations on patient 12, IMD 14 incrementally adjusts (i.e., increaseor decreases) the anodic and cathodic amplitudes, such that at leastsome of the electrode combinations are tested using a plurality ofdifferent anodic and cathodic amplitude combinations. While the activeanode and cathode electrodes in the electrode combination remain thesame, IMD 14 incrementally increases or decreases at least one anodicamplitude and/or at least one cathodic amplitude during the test periodfor the electrode combination. In addition to, or instead of, thelogical and efficient arrangement of electrode combinations discussedabove, the electrode combinations of a predefined set can be arrangedsuch that at least some electrode combinations may be transitioned tothe next electrode combination in the order by an incremental adjustmentto at least one anodic amplitude and/or at least one cathodic amplitude.This technique is described in further detail with respect to FIGS.10A-11D. This arrangement of electrode combinations within a predefinedset may enable IMD 14 to transition between electrode combinations withminimal or no discomfort to patient 12.

In addition, in some examples, the electrode combinations of the set arearranged in the predetermined order such that electrode combinationsbeing tested are propagated down the lead, e.g., from a proximal end ofthe lead to a distal end of the lead or vice versa, as electrodecombinations are tested in the predetermined order. In this way, a setof test electrode combinations may be configured to test electrodecombinations at different target tissue sites in a logical and efficientmanner. The proximal end of lead 16A may be the end closest to IMD 14when IMD 14 is electrically connected to IMD 14.

In some examples, the set of electrode combinations in the predeterminedorder define a predetermined sequence of electrode patterns, eachelectrode pattern defining a relative arrangement between one or moreanodes and one or more cathodes of the respective electrode pattern. Theelectrode patterns in the sequence are predetermined, and, therefore,define a predetermined group of electrode patterns. An electrodecombination may be defined by a subset of electrodes of lead 16A, andthe polarities of the particular electrodes. Thus, the electrodecombination may be defined by a subset of electrodes of lead 16A and anelectrode pattern. The length of the sequence (e.g., the number ofelectrode combinations in the sequence) can be any suitable size, suchas eight electrode combinations, 10 electrode combinations, 16 electrodecombinations, 20 electrode combinations, or 32 electrode combinations,although the sequence can include a fewer or greater number of electrodecombinations. The sequence may be selected in some examples such thatadjacent electrode combinations have different electrode patterns.

Electrode patterns of the predetermined group can be selected using anysuitable technique. The electrode patterns may be, for example, a groupof electrode patterns known to the clinician or to another entity (e.g.,a manufacturer of IMD 14 or leads 16) to be potentially effective oreffective for a particular patient condition or one or more symptoms,based on historical data, computer modeling of the electricalstimulation, user experience data, or any combination thereof. In someexamples, the electrode patterns of the predetermined group arepreselected, e.g., by a manufacturer of IMD 14, and may not be modifiedby the user. In other examples, the user may select the electrodepatterns, e.g., by selecting between a bipolar sequence and a unipolarsequence (e.g., cathodes on a lead and anodes on IMD 14 housing).

In some examples, every electrode pattern of the group of electrodepatterns that define the predefined set of electrode combinations areselected such that the anode and cathode electrodes of every electrodepattern in the predefined set are programmed together on adjacentelectrodes without any inactive (also referred to as “off” or “unused”)electrodes between the active electrodes. As a result, in some examples,every electrode combination in the predefined set includes activeelectrodes that are immediately adjacent to each other and interruptedby inactive electrodes. This type of arrangement of anode and cathodeelectrodes may minimize the area of activation of the neurons as theelectrode combinations propagate down the electrode array. As a result,the electrical stimulation via may be more precise.

In other examples, however, the group of electrode patterns includes atleast one electrode pattern in which at least two active electrodes areseparated by at least one inactive electrode, as shown in FIGS. 6-11Dwith electrode combinations C and CC, which each have one inactiveelectrode between active electrodes.

In some examples, at least one electrode pattern of the predeterminedgroup may appear multiple times at different positions in thepredetermined sequence. For example, the predetermined sequence may becomprised of a repeating sub-sequence of electrode patterns (e.g., asequence cycled through at least twice when all of the electrodecombinations of the set are tested). The sub-sequence of electrodepatterns may be repeated as, for example, test electrode combinationsare propagated down lead 16A. Thus, in some examples in which programmer18 tests a predefined set of electrode combinations on patient 12,programmer 18 automatically selects (e.g., with little to no userintervention) a plurality of different electrode combinations of the setby at least moving one or more electrode patterns (e.g., two or morepatterns) down lead 16A in a systematic manner, e.g., from a proximalend of lead 16A to a distal end of lead 16A, or vice versa. In theseexamples, the position of a particular electrode pattern in the sequencemay indicate the axial position along lead 16A at which the electrodepattern is tested on patient 12. In other examples, however, theplurality of electrode patterns may be arranged in the sequence in anon-repeating order.

Lead 16A (as well as lead 16B) defines a plurality of levels ofelectrodes, each level including at least one electrode and beingseparated from an adjacent level in an axial direction (e.g., in adirection substantially parallel to a longitudinal axis of lead 16A, thelongitudinal axis extending between a proximal end and a distal end oflead 16A). As two or more electrode patterns are moved down lead 16A,the electrode patterns are moved through the levels of lead 16A, e.g.,from a proximal end of the lead to a distal end of the lead or viceversa. Moving two or more electrode patterns down lead 16A in asystematic manner results in a plurality of different electrodecombinations. Levels of leads 16A, 16B may correspond to each otherbased on the relative alignment of the levels when leads 16A, 16B areimplanted in patient 12. For example, if each of leads 16A includes fourlevels of electrodes, leads 16A, 16B may be implanted such that a firstlevel of electrodes of lead 16A substantially aligns with (e.g.,adjacent to) and corresponds to a first level of electrodes of lead 16B,such that a second level of electrodes of lead 16A substantially alignswith (e.g., is adjacent to) and corresponds to a second level ofelectrodes of lead 16B, and so forth. When leads 16A, 16B are implantedin patient 12, electrodes on adjacent leads 16A, 16B may not beprecisely aligned, e.g., at the same height, but may still be consideredto be at corresponding levels.

Ordering electrode combinations of the set such that two or moreelectrode patterns are shifted down lead 16A in a systematic mannerenables the electrode patterns to be tested at different axial positions(e.g., positions along a longitudinal axis) of lead 16A in an orderlyand logistic manner without moving lead 16, thereby providing anefficient way to explore the electrode space defined by a given lead 16(or set of leads 16), allowing many electrode patterns to be tried atdifferent axial positions in quick succession. When lead 16A isimplanted in patient 12, electrodes at different axial positions of lead16A may be proximate to different tissue sites. Because the tissue sitemay affect the efficacy of electrical stimulation, the efficacy ofelectrical stimulation may differ depending on the axial position of theelectrodes with which IMD 14 delivers electrical stimulation. In thisway, the axial position along lead 16A may affect the therapeuticefficacy of a particular electrode pattern.

The electrode combinations in the set, as well as the order of electrodecombinations within the set, provide a useful starting point foridentifying one or more electrode combinations for deliveringefficacious electrical stimulation therapy to patient 12. The automaticselection of electrode combinations for testing by IMD 14 or programmer18 may be more efficient (e.g., consume less time) than the manualselection of the same electrode combinations by a clinician. Programmer18 may be configured such that once the testing is initiated, e.g., by aclinician interacting with programmer 18, programmer 18 automaticallycontrols IMD 14 to generate and deliver electrical stimulation therapyto patient 12 via each electrode combination of a plurality ofpredetermined electrode combinations in the predetermined order. Theautomated selection of electrode combinations to test may eliminate orat least reduce the interaction required by the clinician during aprogramming session.

The testing of a set of electrode combinations defining a sequence oftwo or more electrode patterns may also be more efficient than atechnique in which a plurality of electrode patterns are tested bytesting one electrode pattern at a time by shifting the electrodepattern down the lead to test the electrode pattern at different axialpositions. Rather than moving one electrode pattern at a time todifferent axial positions and consuming time to shift the same electrodepattern to the different axial positions and repeating the process foranother electrode pattern, some example techniques described hereininterleave the electrode patterns being tested as electrode combinationspropagate down the lead. The electrode combinations in the predefinedset being tested may be ordered such that electrode combinations includeat least one anode or cathode from the previous electrode combination inthe predetermined order, such that the transitions between electrodecombinations is relatively fluid and efficient. This type of transitionbetween electrode combinations may not be possible if one electrodepattern at a time is tested on patient 12.

In some examples, IMD 14 may generate the electrical stimulation signaldelivered via each of the electrode combinations of a set with a commonset of other stimulation parameter values (e.g., current or voltageamplitude and frequency). In this way, the variable that is changing maybe limited to the electrodes with which electrical stimulation isdelivered to patient 12. In addition, another variable that may changeduring the testing of a predefined set of electrode combinations is thedistribution of amplitude between the anodes and between the cathodesfor a particular electrode combination. As discussed above, in someexamples, at least some of the electrode combinations use a plurality ofdifferent anodic and cathodic amplitude settings. The efficacy ofelectrical stimulation according to a particular electrode combinationmay vary depending on the anodic amplitudes and cathodic amplitudes ofeach of the active electrodes. Thus, testing at least some electrodecombinations using a plurality of different anodic and cathodicamplitude setting may help more thoroughly evaluate the efficacy of aparticular electrode combination and identify an efficacious anodicamplitudes and cathodic amplitudes.

In other examples, IMD 14 may generate the electrical stimulation signaldelivered via at least two of the electrode combinations of a set withdifferent stimulation parameter values. Different stimulation parametervalues may be selected if, for example, one set of other stimulationparameter values would result in uncomfortable stimulation for one ormore of the electrode combinations due to the relative position betweenthe electrodes of the electrode combination and the tissue of patient12.

In some examples, during the automatic scanning through the electrodecombinations of a predefined set, a user (e.g., a clinician or patient12) may interact with programmer 18 to modify the stimulation parametervalues with which IMD 14 generates the electrical stimulation signal,e.g., based on the perception of stimulation by patient 12. For example,the user can increase or decrease the intensity of stimulation (e.g., byincreasing or decreasing the total stimulation amplitude) to maintaincomfortable sensations that are strong enough to evaluate the efficacyof the electrode combinations. In some examples, the intensity is onlyincreased for the present electrode combination being tested by IMD 14when the user input modifying the amplitude was received, and thenreturned to a baseline level for subsequently tested electrodecombinations (unless user input is received to change the intensity ofstimulation for those other electrode combinations). In other examples,programmer 18 (or IMD 14) also applies the modified stimulationamplitude to the remaining electrode combinations in the set to betested on patient 12.

Programmer 18 can control when the user modifies the stimulationparameter values during the automatic scanning through the electrodecombinations of a set. For example, programmer 18 may be configured suchthat the user may only modify the stimulation parameter values when IMD14 is not actively changing electrode combinations or anodic andcathodic amplitude settings, e.g., when the automatic scanning ispaused.

In some examples, the efficiency of the electrode combination testingprocess may be further improved by reducing the amount of input frompatient 12. For example, patient 12 may only provide efficacy feedbackwhen efficacious electrical stimulation is perceived, e.g., by providinginput to programmer 18 (directly or indirectly, e.g., via a clinician).In response to receiving the input, programmer 18 may store informationidentifying the electrode combination that the input is associated with,e.g., by marking the electrode combination with which IMD 14 wasdelivering electrical stimulation when the efficacious electricalstimulation was perceived by patient 12. In examples in which at leastsome electrode combinations are tested at a plurality of differentanodic amplitude and cathodic amplitude combinations, the informationidentifying the electrode combination can include informationidentifying the anodic amplitude and cathodic amplitude combinationassociated with the input.

After the testing of the set of electrode combinations, the markedelectrode combinations (and any associated information, such as theanodic amplitude and cathodic amplitude combination) may then be used toprogram one or more therapy parameters, for identification of additionalelectrode combinations to test on patient 12, or any other use. In thisway, patient 12 may only intervene with efficacy feedback whenefficacious electrical stimulation is perceived and system 10 mayotherwise automatically test the set of electrode combinations. Theefficacy of the electrical stimulation may be, for example, based on thereduction in one or more symptoms of a patient condition, relatively lowside effects from the electrical stimulation therapy, or somecombination of both. When patient 12 intervenes with the efficacyfeedback, the clinician may pause the delivery of test electricalstimulation according to the set of electrode combinations, or may letthe automatic testing of the set of electrode combinations continuewithout pausing or otherwise stopping the automatic testing process.

In contrast to a system in which a clinician manually selects anelectrode combination, and then patient 12 provides efficacy feedbackfor the selected combination prior to the selection of another electrodecombination by the clinician, prior to the delivery of electricalstimulation by IMD 14 via another electrode combination, or both, system10 is configured to automatically test a set of electrode combinationsin a predetermined order without requiring the clinician to modify theelectrode combinations, without requiring the clinician to manuallycontrol IMD 14 to deliver electrical stimulation via each electrodecombination, or without requiring patient 12 to provide input for eachelectrode combination prior to testing another electrode combination maybe more efficient. The efficiency may be at least partially attributableto the reduction in the amount of time between the testing of differentelectrode combinations. In addition, the time required to receivepatient input for electrode combinations that are not efficacious may beeliminated. In some techniques described herein, programmer 18 or aclinician may determine that an electrode combination being tested isnot efficacious unless the patient indicates otherwise. This may helpreduce the total amount of time consumed to test a plurality ofelectrode combinations.

Some clinicians or patients may prefer to provide efficacy input foreach tested electrode combination. Thus, in other examples describedherein, patient 12 may provide feedback for each tested electrodecombination. Even with feedback from patient 12 for each testedelectrode combination, rather than for only the efficacious electrodecombinations, the automatic testing of a set of electrode combinationsin a predetermined order and without requiring clinician intervention toselect a next electrode combination to test may be more efficient thanexisting devices, systems, and techniques in which each electrodecombination is manually selected and a clinician is required to takesome action between tested electrode combinations to control thedelivery of electrical stimulation via an electrode combination to betested.

FIG. 2 is functional block diagram illustrating components of an exampleIMD 14. FIG. 2 also illustrates leads 16A, 16B and the respective setsof electrodes 24A-24H (collectively referred to as “electrodes 24”),26A-26H (collectively referred to as “electrodes 26”). In the exampleshown in FIG. 2, IMD 14 includes processor 30, memory 32, stimulationgenerator 34, sensing module 36, telemetry module 40, and power source42. Memory 32, as well as other memories described herein, may includeany one or more volatile or non-volatile media, such as a random accessmemory (RAM), read only memory (ROM), non-volatile RAM (NVRAM),electrically erasable programmable ROM (EEPROM), flash memory, and thelike. Memory 32 may store computer-readable instructions that, whenexecuted by processor 30, cause IMD 14 to perform various functionsdescribed herein.

In the example shown in FIG. 2, the set of electrodes 24 of lead 16Aincludes electrodes 24A, 24B, 24C, 24D, 24E, 24F, and 24H, and the setof electrodes 26 of lead 16B includes electrodes 26A, 26B, 26C, 26D,26E, 26F, and 26H. As shown in FIGS. 1 and 2, leads 16 can be implantedin patient 12 such that they are substantially parallel to each otherand spinal cord 18, on substantially opposite sides of spinal cord 18,at approximately the same height relative to spinal cord 18, andoriented such that the distal ends of leads 16 are higher relative tothe spinal cord than the proximal ends of leads 16. Therefore, theillustrated configuration of electrodes 24, 26 may be described as atwo-by-eight, side-by-side, upwardly oriented configuration. Such aconfiguration may be useful for some types of SCS therapy. Otherconfigurations are also contemplated and may depend on the patientcondition for which system 10 is implemented to treat. In addition, insome examples, system 10 includes only one lead 16 (which may define aone-dimensional or two-dimensional array of electrodes) or more than twoleads 16, such as three leads.

In the example shown in FIG. 2, memory 32 stores therapy programs 44,electrode combinations 46, and operating instructions 48, e.g., inseparate memories within memory 32 or separate areas within memory 32.Each stored therapy program 44 defines a particular program of therapyin terms of respective values for a set of electrical stimulationparameters, such as an electrode combination, current or voltageamplitude, and, if stimulation generator 34 generates and deliversstimulation pulses, the therapy programs may define values for a pulsewidth and pulse rate of a stimulation signal. In some examples, thetherapy programs may be stored as a therapy group, which defines a setof therapy programs with which stimulation may be generated. Thestimulation signals defined by the therapy programs of the therapy groupmay be delivered together on an overlapping or non-overlapping (e.g.,time-interleaved) basis.

Electrode combinations 46 stored by memory 32 include a plurality ofpredetermined electrode combinations to be tested (also referred toherein as “test electrode combinations”) on patient 12 to identify anefficacious electrode combination, e.g., during a programming sessionwith a clinician. Electrode combinations 46 may be organized as one ormore sets of predetermined electrode combinations, where the electrodecombinations of a particular set are arranged in a predetermined order,as discussed above. The predetermined electrode combinations of aparticular set may include electrode combinations selected and arrangedin the set, for example, at some point prior to initiating the automatictesting of the electrode combinations in the set on patient 12. Inexamples in which IMD 14 stores test electrode combinations 46,processor 30 may initiate the delivery of electrical stimulation via aparticular set of electrode combinations in response to receive acontrol signal from programmer 18 or another device.

The electrode combinations that are organized into a common set ofelectrode combinations may be selected (by a clinician, by a distributorof IMD 14, or another entity) based on one or more criteria, such as,but not limited to, the electrode patterns defining the electrodecombinations. As discussed above, the electrode patterns may be two ormore electrode patterns known to the clinician or to another entity tobe potentially effective or effective for a particular patient conditionor one or more symptoms, based on historical data.

In other examples, IMD 14 does not store test electrode combinations 46,but, rather, the test electrode combinations may be stored by anotherdevice, such as programmer 18 (FIG. 1). In these examples, programmer 18(or the other device) may transmit (e.g., via a wireless communicationlink) the test electrode combinations to IMD 14. Processor 30 mayreceive the test electrode combinations from programmer 18 via telemetrymodule 40 and control stimulation generator 34 to generate and deliverelectrical stimulation therapy to patient 12 via each of the electrodecombinations, e.g., in accordance with one or more example techniquesdescribed herein.

Operating instructions 48 guide general operation of IMD 14 undercontrol of processor 30, and may include instructions for controllingthe delivery of electrical stimulation to patient 12 via each of theplurality of test electrode combinations 46. The instructions forcontrolling the delivery of electrical stimulation to patient 12 viaeach of the plurality of test electrode combinations 46 may include, forexample, the duration of time electrical stimulation is delivered topatient 12 via each test electrode combination (also referred to hereinas a “test period”), and, in some examples, the predetermined order inwhich the test electrode combinations of a set are tested. In addition,the instructions for controlling the delivery of electrical stimulationto patient 12 can include the instructions with which IMD 14incrementally modifies at least one anodic amplitude or at least onecathodic amplitude for a particular electrode combination during thetest period for the electrode combination. Such information may includethe minimum amplitude increments and the time between amplitudeadjustments.

In other examples, however, the incremental adjustments to the at leastone anodic amplitude or at least one cathodic amplitude is controlled byprogrammer 18 or another device, such as a remote computing device.

Stimulation generator 34 is electrically coupled to each of theelectrodes 24, 26 via conductors of the respective lead 16A, 16B.Stimulation generator 34 may include stimulation generation circuitryconfigured to generate stimulation pulses or waveforms and circuitry forswitching stimulation across different electrode combinations, e.g., inresponse to control by processor 30. Stimulation generator 34 isconfigured to, under the control of processor 30, generate electricalstimulation signals and deliver the electrical stimulation signals topatient 12 via selected electrode combinations. In some examples,stimulation generator 34 generates and delivers electrical stimulationsignals to one or more target tissue sites in patient 12 via a selectelectrode combination based on one or more stored therapy programs 44.The target tissue sites for stimulation signals or other types oftherapy and stimulation parameter values may depend on the patientcondition for which therapy system 10 is implemented to manage.

Stimulation generator 34 may be a single channel or multi-channelstimulation generator. In particular, stimulation generator 34 may becapable of delivering, a single stimulation pulse, multiple stimulationpulses or a continuous signal at a given time via a single electrodecombination or multiple stimulation pulses at a given time via multipleelectrode combinations. In examples in which stimulation generator 34 isa single channel stimulation generator, stimulation generator 34 isconfigured to output electrical stimulation signals via a singlechannel. In examples in which stimulation generator 34 is amulti-channel stimulation generator, stimulation generator 34 isconfigured to output electrical stimulation signals via a single channel(e.g., via a single electrode combination) or via multiple channels(e.g., via multiple electrode combinations) at different times (e.g., ona time-interleaved basis) or simultaneously using a single stimulationengine or multiple stimulation engines.

In some examples, stimulation generator 34 includes a plurality ofstimulation engines that provide a current source and a current sink foreach electrode 24, 26 electrically coupled to IMD 14 to be driven by thestimulation engines. In examples in which stimulation generator 34 isconfigured to deliver current-controlled electrical stimulation,processor 30 is configured to control the stimulation engines toselectively source or sink current via each electrode at a variety ofcurrent amplitudes. In other examples, stimulation generator 34 isconfigured to deliver voltage-controlled electrical stimulation.

In other examples, stimulation generator 34 includes a fewer number ofstimulation engines, e.g., one or more stimulation engines are sharedfor two or more electrodes, and IMD 14 includes a switch module, andprocessor 30 may be configured to control the switch module to apply thestimulation signals generated by stimulation generator 34 to selectedcombinations of electrodes 24, 26. The switch module may be, forexample, a switch array, switch matrix, multiplexer, or any other typeof switching module configured to selectively couple stimulation energyto selected electrodes 24, 26. In some examples in which IMD 14 includesa switch module, stimulation generator 34 and the switch module may beconfigured to deliver multiple channels on a time-interleaved basis. Forexample, the switch module may serve to time divide the output ofstimulation generator 34 across different electrode combinations atdifferent times to deliver multiple programs or channels of stimulationenergy to patient 12.

During a programming session for selecting one or more efficaciouselectrode combinations for later storage as part of one or more therapyprograms 44, stimulation generator 34 may, under the control ofprocessor 30 or programmer 18, or both, automatically generate anddeliver electrical stimulation therapy to patient 12 via each electrodecombination of a predefined set of test electrode combinations 46 storedby memory 62 (or another memory). In examples in which the plurality oftest electrode combinations are tested in a predetermined order,processor 30 may control the order based on the order in which the testelectrode combinations are stored by memory 32, based on the orderprovided by programmer 18, based on the order stored by operatinginstructions 48, or based on other control information.

The processors described in this disclosure, including processor 30, mayinclude one or more digital signal processors (DSPs), general purposemicroprocessors, application specific integrated circuits (ASICs), fieldprogrammable logic arrays (FPGAs), or other equivalent integrated ordiscrete logic circuitry, or combinations thereof. The functionsattributed to processors described herein may be provided by a hardwaredevice and embodied as software, firmware, hardware, or any combinationthereof. Processor 30 is configured to control stimulation generator 34according to therapy programs 44 stored in memory 32 to apply particularstimulation parameter values specified by one or more programs, such asamplitude, pulse width, and pulse rate.

In the example shown in FIG. 2, sensing module 36 is electricallycoupled to each of the electrodes 24, 26 via conductors of therespective lead 16A, 16B. Although not shown in FIG. 2, IMD 14 mayinclude a switch array or the like to selectively electrically connectelectrodes 24, 26 to stimulation generator 34 or sensing module 36.Sensing module 36, under the control of processor 30, is configured tosense one or more physiological parameters of patient 12 via a selectedsubset of electrodes 24, 26 or with one or more electrodes 24, 26 and atleast a portion of a conductive outer housing 50 of IMD 14, an electrodeon an outer housing of IMD 14 or another reference. The sensedphysiological parameters may be used for one or more purposes, such asto control therapy delivery by IMD 14, determine the efficacy of testelectrode combinations, or monitor a health status of patient 12. Insome examples, a set of electrode combinations may be automaticallytested on patient 12 more than one time, e.g., for each of a pluralityof different posture states (e.g., a patient posture or a combination ofposture and activity) of patient 12, and sensing module 36 may beconfigured to generate a signal indicative of the patient posture state.For example, sensing module 36 may include one or more accelerometers,such as a three-axis accelerometer, capable of detecting staticorientation or vectors in three-dimensions.

Although sensing module 36 is incorporated into a common housing 50 withstimulation generator 34 and processor 30 in FIG. 2, in other examples,sensing module 36 is in a separate outer housing from outer housing 34of IMD 14 and communicates with processor 30 via wired or wirelesscommunication techniques. In other examples, system 10 does not includesensing module 36.

Telemetry module 40 is configured to support wireless communicationbetween IMD 14 and an external programmer 18 or another computing deviceunder the control of processor 30. Processor 30 of IMD 14 may receive,e.g., as updates to stored therapy programs 44, values for variousstimulation parameters such as amplitude and electrode combination, fromprogrammer 18 via telemetry module 40. The updates to the therapyprograms may be stored within therapy programs 44 portion of memory 32.In addition, in some examples, processor 30 receives a plurality of testelectrode combinations, other stimulation parameter values for useduring the testing of electrode combinations, or both, from programmer18 via telemetry module 40. Telemetry module 40 in IMD 14, as well astelemetry modules in other devices and systems described herein, such asprogrammer 18, may accomplish communication by RF communicationtechniques. In addition, telemetry module 40 may communicate withexternal medical device programmer 18 via proximal inductive interactionof IMD 14 with programmer 18. Accordingly, telemetry module 40 may sendinformation to external programmer 18 on a continuous basis, at periodicintervals, or upon request from IMD 14 or programmer 18. For example,processor 30 may transmit brain state information 76 to programmer 18via telemetry module 40.

Power source 42 is configured to deliver operating power to variouscomponents of IMD 14. Power source 42 may include a small rechargeableor non-rechargeable battery and a power generation circuit to producethe operating power. Recharging may be accomplished through proximalinductive interaction between an external charger and an inductivecharging coil within IMD 14.

FIG. 3 is a functional block diagram illustrating components of anexample medical device programmer 18 (FIG. 1). Programmer 18 includesprocessor 60, memory 62, telemetry module 64, user interface 66, andpower source 68. Processor 60 is configured to control telemetry module64 and user interface 66, and store and retrieve information andinstructions to and from memory 62. Programmer 18 may be configured foruse as a clinician programmer or a patient programmer. Processor 60 maycomprise any combination of one or more processors including one or moremicroprocessors, DSPs, ASICs, FPGAs, or other equivalent integrated ordiscrete logic circuitry. Accordingly, processor 60 may include anysuitable structure, whether in hardware, software, firmware, or anycombination thereof, to perform the functions ascribed herein toprocessor 60. In some examples, processor 60 of programmer 18 mayperform any part of the techniques described above with respect toprocessor 30 of IMD 14. In addition, in some examples, processor 30 mayperform any part of the techniques described with respect to processor60 of programmer 18.

A user, such as a clinician or patient 12, may interact with programmer18 via user interface 66. User interface 66 includes a display (notshown), such as a liquid crystal display (LCD) or light emitting diode(LED) display or other type of screen, with which processor 60 maypresent information related to therapy, information that indicateselectrode combinations of a set of electrode combinations available fortesting on patient 12, electrode combinations tested on patient 12, orefficacy information for tested electrode combinations (e.g., patientefficacy ratings, physiological data, or any combination thereof). Inaddition, user interface 66 may include an input mechanism configured toreceive input from the user. The input mechanisms may include, forexample, buttons, a keypad (e.g., an alphanumeric keypad), a peripheralpointing device, a touchscreen display, or another input mechanism thatallows the user to navigate though user interfaces presented byprocessor 60 of programmer 18 and provide input.

In some examples, the user may interact with user interface 66 tocontrol the therapy delivery by IMD 14. For example, the user mayprovide input via user interface 66 to adjust the overall intensity ofthe electrical stimulation during the testing of a plurality ofelectrode combinations of a predefined set. The user may, for example,decrease the stimulation amplitude when the electrical stimulationbecome uncomfortable or increase the overall intensity of thestimulation when patient 12 can no longer perceive the electricalstimulation or desires a higher intensity electrical stimulation. Inresponse to such user input, processor 60 may control IMD 14 (e.g., bytransmitting a control signal to IMD 14) to adjust the amplitude ofelectrical stimulation delivered via the electrode combinations of theset of electrode combinations. As discussed above, programmer 18 maytemporarily suspend testing of a plurality of electrode combinations tohold the electrode combination being tested steady while a user modifiesone or more stimulation parameter values.

If programmer 18 includes buttons and a keypad, the buttons may bededicated to performing a certain function, i.e., a power button, or thebuttons and the keypad may be soft keys that change function dependingupon the section of the user interface currently viewed by the user. Inaddition, or instead, the screen (not shown) of programmer 18 may be atouch screen that allows the user to provide input directly to a GUIpresented on the display. The user may use a stylus or their finger toprovide input to the display. In other examples, user interface 66 alsoincludes audio circuitry for providing audible notifications,instructions or other sounds to patient 12, receiving voice commandsfrom patient 12, which may be useful if patient 12 has limited motorfunctions.

The user may also interact with user interface 66 to manually change thestimulation parameter values of a therapy program, manually selecttherapy programs, generate new therapy programs, transmit new therapyprograms to IMD 14, view therapy information, control the automatictesting of a set of electrode combinations by programmer 18 and IMD 14(e.g., initiate the testing process, pause the testing process, orpermanently stop the testing process), or otherwise communicate with IMD14. An example GUI that may be displayed via a display of user interface66 for controlling the automatic testing of a set of electrodecombinations is described below with respect to FIG. 12.

In some examples, at least some of the control of therapy delivery byIMD 14 may be implemented by processor 60 of programmer 18. For example,processor 60 may control the therapy parameter values, timing, or both,of the generation and delivery of electrical stimulation to patient 12during a programming session in which a plurality of electrodecombinations are tested on patient 12. As another example, processor 60may control incremental changes to the distribution of amplitude betweenanodes and between cathodes of a particular electrode combination, i.e.,changes to the anodic amplitude settings or cathodic amplitude settings,during the testing of the electrode combination. As discussed above, theautomatic modification to one or more anodic amplitudes, one or morecathodic amplitudes, or both, during the testing of a particularelectrode combination may enable the electrode combination to be morethoroughly tested in an efficient manner. In other examples, processor30 of IMD 14 may control one or more these aspects of the generation anddelivery of electrical stimulation to patient 12 during the programmingsession.

Memory 62 is configured to store data. Memory 62 may include anyvolatile or nonvolatile memory, such as RAM, ROM, EEPROM or flashmemory. Memory 62 may also include a removable memory portion that maybe used to provide memory updates, increases in memory capacities, orstorage of sensitive patient data. Memory 62 may store instructions forexecution by processor 60, such as, but not limited to, instructions foroperating user interface 66 and telemetry module 64, and for managingpower source 68. Memory 62 may also store therapy data retrieved fromIMD 14 during the course of therapy or during a programming session.

Memory 62 may store instructions for execution by processor 60 toimplement the electrode combination search techniques described herein,including the search technique described with respect to FIG. 4A. In theexample shown in FIG. 3, memory 62 stores test electrode combinations70, which includes one or more predefined sets of electrode combinationsto be tested on patient 12 in order to identify one or more efficaciouselectrode combinations, e.g., during a programming session with aclinician. Electrode combinations 70 can be the same as electrodecombinations 46 described with respect to FIG. 2. As discussed above, insome examples, test electrode combinations 70 are stored by onlyprogrammer 18 (in which case IMD 14 does not store test electrodecombinations 46), only IMD 14 (in which case programmer 18 does notstore test electrode combinations 70), or both IMD 14 and programmer 18.

Memory 62 may also store information relating to the plurality of testedelectrode combinations, which may facilitate the identification ofefficacious electrode combinations by the clinician. The clinician mayreference the stored information for one or more purposes, such as todetermine one or more electrode combinations for programming IMD 14 forchronic stimulation therapy or for further trialing on patient 12. Theinformation can include efficacy information, such as, but not limitedto, any one or more of efficacy markers, subjective efficacy ratingsprovided by patient 12 for a specific tested electrode combination orone or more sensed physiological parameter values indicative of theefficacy of the associated electrode combination. An efficacy ratingprovided by patient 12 may take any suitable format. In some examples,the efficacy rating can be any one or more of a numerical rating on apredefined scale (e.g., a scale of 1-10), a another type of rating(e.g., a rating using the Wong-Baker FACES Pain Rating Scale), or a painmap that indicates the area of paresthesia resulting from the deliveryof electrical stimulation via a particular electrode combination. Therating can indicate the reduction in symptoms of the patient condition,the severity of the side effects resulting from the electricalstimulation therapy, or both.

Processor 60 may be configured to present, e.g., via a display of userinterface 66, a list of tested electrode combinations and theirassociated information (e.g., efficacy information), where available.For example, in some examples, a user may interface with user interface66 to input a request to view the predefined set of test electrodecombinations, which can include, in some examples, an indication of theautomatic anodic and/or cathodic amplitude adjustments for each of thetest electrode combinations for which the amplitudes will beautomatically adjusted. In response to receiving the user input,processor 60 may generate and present a display via user interface 66that indicates the electrode combinations (which can be identified byname, diagram, or any other identifier) of the set. In addition, in someexamples, processor 60 is configured to, in response to receiving a userrequest via user interface 66, order the list according to the efficacyratings or another parameter.

Programmer 18, alone or with the aid of a user, may create therapyprograms that include the identified efficacious electrode combinations.Processor 60 may be configured to transmit the therapy programs to IMD14, e.g., via the respective telemetry modules 64, 40.

Wireless telemetry in programmer 18 may be accomplished by RFcommunication or proximal inductive interaction of external programmer18 with IMD 14. This wireless communication is possible through the useof telemetry module 64. Accordingly, telemetry module 64 may be similarto the telemetry module 40 of IMD 14. In other examples, programmer 18may be capable of infrared communication or direct communication througha wired connection. In this manner, other external devices may becapable of communicating with programmer 18 without needing to establisha secure wireless connection.

Power source 68 is configured to deliver operating power to thecomponents of programmer 18. Power source 68 may include a battery and apower generation circuit to produce the operating power. In someexamples, the battery may be rechargeable to allow extended operation.In addition, programmer 18 may be directly coupled to an alternatingcurrent outlet to operate.

In some cases, external programmer 18 may be characterized as aphysician or clinician programmer if it is primarily intended for use bya physician or clinician. In other cases, external programmer 18 may becharacterized as a patient programmer if it is primarily intended foruse by patient 12. A patient programmer is generally accessible topatient 12 and, in many cases, may be a portable device that mayaccompany the patient throughout the patient's daily routine. Aphysician or clinician programmer may support selection and generationof programs by a clinician for use by IMD 14, whereas a patientprogrammer may support adjustment and selection of such programs bypatient 12 during ordinary use.

In some example techniques described herein for identifying one or moreelectrode combinations that may provide efficacious (e.g., beneficial)therapy for patient 12, IMD 14 delivers electrical stimulation topatient 12 via a plurality of electrode combinations of a predefined setin a predetermined order. For example, under the control of programmer18, IMD 14 may deliver electrical stimulation energy via a firstelectrode combination of the set for a first test period, terminatedelivery of stimulation via the first electrode combination, deliverelectrical stimulation energy via a second electrode combination of theset for a second test period, terminate delivery of stimulation via thesecond electrode combination, deliver electrical stimulation energy viaa third electrode combination of the set, and so forth, through an nthelectrode combination of the set including n-number of electrodecombinations, or until the clinician or patient 12 stops the testing.The clinician or patient may return to electrode combinations of the setthat were marked as relatively efficacious and use those electrodecombinations to identify one or more efficacious electrode combinationsfor patient 12.

The transitions between electrode combinations of a set in thepredetermined order are selected to be efficient and comfortable topatient 12. For example, the n-number of electrode combinations may bearranged in the set such that adjacent electrode combinations share atleast one anode electrode or at least one cathode electrode. Inaddition, the plurality of electrode combinations of the set includeelectrode combinations defined by a respective one of at least twoelectrode patterns, such that multiple electrode patterns may be testedon patient 12. In some examples, at least some of the electrodecombinations of the set are tested at a plurality of different anodicand cathodic amplitude combinations. In these examples, the transitionsbetween electrode combinations may also be relatively efficient andcomfortable to patient 12 due to the manner in which at least one of theanodic amplitudes and/or at least one of the cathodic amplitudes areincrementally adjusted. For example, a transition from a first electrodecombination to a second electrode combination may occur after anincremental adjustment to one or more of the anodic amplitudes orcathodic amplitudes of the first electrode combination. Thus, thetransition to the second electrode combination may be relatively fluid.

FIG. 4A is a flowchart illustrating an example technique for identifyingone or more electrode combinations that may provide efficacious therapyfor patient 12. While different aspects of the technique shown in FIG.4A are described with specific reference to processor 30 of IMD 14 andprocessor 60 of programmer 18, in other examples, any part of or theentire technique described with respect to FIG. 4A may be performed byprocessor 30 or processor 60 or a processor of another device. Forexample, part or all of the control of the testing of a set of electrodecombinations may be performed by a computing device remotely locatedrelative to programmer 18, IMD 14, or both, such as, but not limited to,a cloud computing device.

In some examples, the remote computing device may store one or more setsof test electrode combinations and communicate the one or more sets oftest electrode combinations to programmer 18 or directly to IMD 14. Inaddition, or instead, the remote computing device may controlincremental modifications to the anodic amplitudes and/or cathodicamplitudes during the delivery of electrical stimulation according toeach tested electrode combination, e.g., as described with respect toFIGS. 10A-11D. The cloud computing device may be configured to beaccessed by multiple individual devices (e.g., multiple programmers 18)as needed, where the individual devices may or may not be located withinthe same location. In this way, in some examples, the cloud computingdevice may service more than one clinic.

In the technique shown in FIG. 4A, processor 60 of programmer 18controls IMD 14 to deliver electrical stimulation to patient 12 with anelectrode combination selected from a predefined set of a pluralityelectrode combinations (80). Processor 60 may control IMD 14 using anysuitable technique, such as by transmitting a control signal toprocessor 30 of IMD 14 via the respective telemetry modules 64, 40, and,in response to receiving the control signal, processor 30 may controlstimulation generator 44 to generate and deliver electrical stimulationtherapy to patient 12 via the selected electrode combination.

In some examples, processor 60 is configured to automatically controlthe timing, electrode combination, and anodic and cathodic amplitudesettings with which IMD 14 delivers electrical stimulation to patient12, i.e., without any user interaction other than user interactionstarting the automatic scan through the predefined set of electrodecombinations and user interaction stopping or pausing the automaticscan. This may help reduce the amount of time consumed to test theefficacy of the electrode combinations of the predefined set and limitthe user interaction, which may help reduce the burden on a user. Asdiscussed below, however, processor 60 may be configured to responsivelycontrol the automatic scan through the electrode combinations inresponse to intervening user input (received after the start of theautomatic scan). However, processor 60 is configured, in some examples,to complete the automatic scan through the electrode combinations of thepredefined set after processor 60 initiates the automatic scan, e.g., inresponse to user input, without any further user input after the scan isinitiated. In this way, user interaction may not be required to proceedto the next step of the scan (e.g., the next test electrodecombination).

In examples in which electrode combinations are propagated down lead 16Aas the testing of the set progresses, the first electrode combination inthe set of electrode combinations being tested on patient 12 may includethe proximal-most electrode if the electrode combinations are shiftedtowards a distal end of lead 16A or the distal-most electrode if theelectrode combinations are shifted towards a proximal end of lead 16A.However, the first electrode combination in the set may have othersuitable configurations. For example, if the clinician only wants totest certain electrodes of lead 16A, the clinician may choose a startingelectrode for the testing, and processor 60 may then start the automatictesting using the electrode combination of the set having aproximal-most cathode at the starting electrode in examples in whichelectrode combinations are shifted towards a distal end of lead 16A or adistal-most cathode at the starting electrode in examples in whichelectrode combinations are shifted towards a proximal end of lead 16A.For example, the steps required in the set of electrode combinationshown in FIG. 6 and described in further detail below to propagate downthe lead from electrode combination A to electrode combination E isdifferent than the steps shown from electrode combination E to electrodecombination M due to electrode combination A beginning with the cathodeat the distal-most electrode.

IMD 14 may generate electrical stimulation energy delivered to patient12 via the selected electrode combination using a stored set ofstimulation parameter values or using stimulation parameter valuestransmitted to IMD 14 by processor 60 of programmer 18. The initialstimulation amplitude may be set at, for example, a level that is knownto be at a perception intensity level (e.g., the lowest intensity levelat which patient 12 may perceive the electrical stimulation) for thefirst electrode combination of the set or an average perceptionintensity level for a plurality of electrode combinations. In otherexamples, the initial stimulation amplitude may be set at zero andincrementally ramped up.

In some examples, IMD 14 is configured to control the anodic amplitudeand cathodic amplitude assigned to each anode and cathode, respectively,of a particular electrode combination. As discussed above, in someexamples, at least some of the electrode combinations are tested at aplurality of different anodic and cathodic amplitude combinations. IMD14, alone or under the control of processor 60 of programmer 18 oranother device, may initiate stimulation delivery according to aparticular electrode combination at a starting anodic and cathodicamplitudes and then incrementally adjust the amplitudes according to apredefined schedule of amplitude adjustments. For example, a test periodduring which an electrode combination is tested on patient 12 may bedivided into a plurality of time slots, and IMD 14 may increase ordecrease the amplitudes by a minimum amplitude adjustment increment ineach time slot according to the predefined schedule.

The minimum amplitude adjustment increments applied by IMD 14 totransition to a next time slot in the schedule may be substantially thesame (e.g., equal or nearly equal) in some examples, and may bedifferent in other examples. For example, the schedule may define two ormore amplitude adjustment increments. In some examples, the scheduleincludes two amplitude adjustment increments that alternate, e.g., inalternating time slots. For example, to transition from a first timeslot to a second time slot, IMD 14 (e.g., under the control of processor60 or processor 30) may adjust at least one cathodic amplitude settingor at least one anodic amplitude setting, or both, by a first amplitudeadjustment increment (e.g., 4%). In this example, to transition from thesecond time slot to a third time slot (immediately following the secondtime slot), IMD 14 may adjust at least one cathodic amplitude setting orat least one anodic amplitude setting, or both, by a second amplitudeadjustment increment (e.g., 6%). Then, to transition from the third timeslot to a fourth time slot (immediately following the third time slot),IMD 14 may adjust at least one cathodic amplitude setting or at leastone anodic amplitude setting, or both, by the first amplitude adjustmentincrement (e.g., 4%). The first and second amplitude adjustments mayalternate in this manner until the end of the schedule is reached.

In some examples, the steps defined by the predefined schedule ofamplitude adjustments are arranged such that adjacent steps include atleast one shared anode electrode and at least one shared cathodeelectrode. This sharing of anodes and cathodes may help reduce theimpact to the electrical stimulation perceived by patient 12 resultingfrom the incremental changes in anodic amplitude, cathodic amplitude, orboth, e.g., when transitioning between electrode combinations. Inaddition, the arrangement in which at least some of the adjacentelectrode combinations of the set include at least one shared anodeelectrode and at least one shared cathode electrode may help minimizethe likelihood that overstimulation will occur suddenly from one step ofthe schedule to another.

In some examples, the set of electrode combinations and, if present, thepredefined schedule of amplitude adjustments, are stored by memory 62 ofprogrammer 18, memory 32 of IMD 14, or both memories 32, 62. The otherstimulation parameter values with which stimulation generator 34generates the electrical stimulation energy delivered via the electrodecombinations, such as the signal amplitude (current or voltage) andfrequency, may be stored by memory 62 of programmer 18, memory 32 of IMD14, or both memories 32, 62. Thus, in some examples, processor 60transmits one or both of the electrode combination and other stimulationparameter values for generating the electrical stimulation energy to IMD14, while, in other examples, the processor 60 controls delivery ofelectrical stimulation by IMD 14 by indicating which of the electrodecombinations and other stimulation parameter values stored by memory 32of IMD 14 should be selected by processor 30 of IMD 14.

As discussed above, an electrode combination can be characterized by thesubset of electrodes 24 used to deliver electrical stimulation and theelectrode pattern defined by the electrodes and the respective polarityof the electrodes. The set of electrode combinations for testing onpatient 12 may be defined as a predetermined group of electrodepatterns, the group including two or more electrode patterns, such astwo, three, four, five, or more electrode patterns. These electrodepatterns of the predetermined group may be referred to as “major”electrode patterns in that they define the plurality of electrodecombinations that are identified for testing on patient 12. Anyelectrode patterns that may result from transitioning from a firstelectrode combination to a second electrode combination, e.g., resultingfrom the incrementally decreasing anodic and/or cathodic amplitudes ofone or more active electrodes of the first electrode combination and theincremental increasing of anodic and/or cathodic amplitudes of one ormore active electrodes of the second electrode combination, may bereferred to as “minor” electrode patterns.

The two or more major electrode patterns in a predetermined group oftest electrode patterns may be, for example, clinically relevantelectrode patterns, and, therefore, a useful starting point forselecting one or more efficacious electrode combinations for patient 12.An electrode pattern may be determined to be clinically relevant by,e.g., a clinician, a manufacturer of IMD 14 or leads 16, or anothersource. In some examples, the clinical relevancy indicates that theelectrode patterns are known to result in efficacious electrodecombinations for at least some patients having a similar or identicalpatient condition as patient 12. Other selection parameters may beimplemented instead of, or in addition to, the similarity in patientcondition, to select the electrode patterns for the predetermined set oftest electrode combination.

In one example, a predetermined group of test electrode patterns fortesting on patient 12 includes four electrode patterns: a first simplebipole (e.g., as shown in the schematic diagram of FIG. 5A), a secondsimple bipole (e.g., as shown in the schematic diagram of FIG. 5B), aguarded cathode (e.g., as shown in the schematic diagram of FIG. 5C),and a guarded double cathode (e.g., as shown in the schematic diagram ofFIG. 5D). These electrode patterns have been found to be clinicallyrelevant for some patients that are candidates for SCS to treat pain. Inother examples, other groups of electrode patterns can be used, whichmay include the same or different electrode patterns as those shown inFIGS. 5A-5D.

Returning again to the technique shown in FIG. 4A, processor 60determines whether user input has been received via user interface 66(82). Processor 60 may make this determination at any suitable time. Forexample, processor 60 may make this determination after controlling IMD14 to deliver electrical stimulation to patient 12 with the selectedelectrode combination (80), or prior to, during, or after controllingIMD 14 to deliver electrical stimulation to patient 12 with the selectedelectrode combination (80).

Processor 60 may receive different types of user input during thedelivery of test electrical stimulation according to a plurality ofelectrode combinations of a predefined set, and each type of user inputmay be associated with a respective responsive action (84). Examples ofuser inputs may include, for example, input marking an electrodecombination, efficacy information, input requesting the automatictesting of the set of electrode combinations be paused, shiftedbackward, or slowed down, input requesting that certain electrodepatterns or electrode combinations be eliminated from the set of testelectrode combinations, or input requesting an electrode combination ata different axial position of lead 16A be tested (e.g., input selectinga start electrode combination at which the test electrical stimulationshould be re-started).

In some examples, programmer 18 is configured such that a user mayprovide input selecting a different electrode combination in the set to“jump” to, but such that the user may not change the order of theelectrode combinations in the set. As discussed above, the order ofelectrode combinations in the set is predetermined and selected toresult in efficient transitions between subsequently tested electrodecombinations.

In response to determining that user input has been received (“YES”branch of block 82), processor 60 may take an action responsive to thetype of user input (84). For example, the user input may provideprocessor 60 with efficacy information that indicates the efficacy ofelectrical stimulation delivered via the selected electrode combinationor another electrode combination. In response to receiving such userinput, processor 60 may store the efficacy information in memory 62,along with an indication of the electrode combination to which theefficacy information relates. The electrode combination may be, forexample, the electrode combination with which IMD 14 was deliveringelectrical stimulation to patient 12 when processor 60 received theefficacy information.

As another example, the user input may be input marking an efficaciouselectrode combination. The user may provide such input when, forexample, patient 12 perceives efficacious electrical stimulation. Inresponse to receive such user input, processor 60 may generate a marker(e.g., a flag, value, or other signal), associate the marker with theelectrode combination with which IMD 14 was delivering electricalstimulation to patient 12 when the marker was received, and store themarker and associated electrode combination in memory 62 (or anothermemory).

In some examples, system 10 is configured such that a user may interruptthe automatic delivery of electrical stimulation to patient 12 via theset of electrode combinations, e.g., to pause the electrical stimulationor to change the position along lead 16A at which the electrodecombinations are being tested (e.g., “jump” to a different positionalong lead 16A). Thus, in some examples, the user input received byprocessor 60 (82) may indicate that the electrode combination testingprocess should be paused (e.g., paused temporarily or stoppedindefinitely). In response to receiving such user input, processor 60may control IMD 14 to pause the delivery of electrical stimulation viathe selected electrode combination. Processor 60 may, for example,transmit a control signal to processor 30 of IMD 14 via the respectivetelemetry modules 64, 40, and, in response to receiving the controlsignal, processor 30 of IMD 14 may control stimulation generator 34 tostop the delivery of electrical stimulation therapy to patient 12 viathe selected electrode combination.

In some examples, user input that requests an electrode combination at adifferent axial position of lead 16A be tested may indicate a targetaxial position of lead 16A for the next tested electrode combination.For example, processor 60 may present a graphical representation of lead16A, including electrodes 24, via a display of user interface 66 and theuser may provide the input by interacting with the graphicalrepresentation of lead 16A. Processor 60 may, in some examples, indicatethe electrode combination with which IMD 14 is currently deliveringelectrical stimulation to patient on the graphical representation oflead 16A. A user may provide input indicating the target axial positionof lead 16A for the test electrical stimulation selected, e.g., byselecting a specific starting electrode 24 on the graphicalrepresentation of lead 16A and electrodes 24. The selected electrode maybe, for example, the proximal-most or distal-most cathode electrode oranode electrode for the next tested electrode combination.

Depending on the implant site of lead 16A, different electrodes 24 oflead 16A may target different tissue sites. Thus, the user may provideinput requesting that an electrode combination at a different axialposition of lead 16A be tested if, for example, patient 12 or theclinician determines that a particular one or more electrodes 24 are notimplanted proximate to a target tissue site in patient 12 and electricalstimulation therapy delivered via such electrodes may not beefficacious.

In response to receiving user input indicating that an electrodecombination at a different axial position of lead 16A be tested,processor 60 may select a different electrode combination for testing onpatient 12 and restart the technique shown in FIG. 4A. Processor 60 may,for example, select the next electrode combination in the predeterminedorder that is at the target axial position selected by the user. Forexample, processor 60 may select the next electrode combination in theset that includes any electrode at the axial position of lead 16Aselected by the user, a proximal-most electrode at the selected axialposition, or a distal-most electrode at the selected axial position oflead 16A.

Any combination of the aforementioned user inputs may be received byprocessor 60.

After taking the responsive action (84) or in response to determining nouser input has been received (“NO” branch of block 82), processor 60determines if there are additional electrode combinations in the set totest (86). In response to determining there are additional electrodecombinations of the set to test (“YES” branch of block 86), processor 60automatically selects a next electrode combination to test (88). Thenext electrode combination may be, for example, determined based on thepredetermined order of the set of electrode combinations. As an example,the next electrode combination may be the electrode combinationimmediately following the previously tested electrode combination in thepredetermined order. After selecting the next electrode combination totest, processor 60 may control IMD 14 to deliver electrical stimulationaccording to the next electrode combination (80).

In some examples of the technique shown in FIG. 4A, instead of sendingseparate control signals to IMD 14 for each tested electrodecombination, processor 60 of programmer 18 may initiate an electrodecombination identification process (in which a plurality ofpredetermined electrode combinations are tested in a predeterminedorder), and processor 30 of IMD 14 may control the automatic selectionof the next electrode combination of the set in the predetermined order.

The electrode combinations of the set of electrode combinations areordered such that transitions between subsequently tested electrodecombinations are efficient. For example, as discussed above, adjacentelectrode combinations in the order include at least one shared anodeelectrode or cathode electrode, which may help reduce the amount of timerequired to increase or decrease the intensity of electrical stimulationdelivered via a particular electrode during a transition betweenelectrode combinations.

Processor 30 may control stimulation generator 34 to shift between testelectrode combinations using any suitable shifting technique. Theshifting technique may be selected to minimize any discomfort to patient12. For example, processor 30 may control the shifting of stimulationparameters smoothly from one electrode combination to a second electrodecombination in a manner gradual enough to allow a user to intervene toadjust the stimulation intensity should the sensation becomeuncomfortable or imperceptible to patient 12 during the shiftingprocess. In some examples, this gradual shifting is accomplished byreducing stimulation amplitude applied by one electrode combination andincreasing stimulation amplitude applied by another electrodecombination in a series of incremental steps to apply stimulation viathe predefined sequence of different electrode patterns.

Processor 30 (or processor 60) may control the rate transition betweenelectrode combinations based on instructions stored by memory 32 orreceived from programmer 18. For example, as described with respect toFIG. 4B, the rate of transition between electrode combinations maydepend on the increments with which anodic and cathodic amplitudes areadjusted to shift between electrode combinations.

The amplitude adjustment increments may affect the duration of timerequired to shift between electrode combinations, and, therefore, theduration of time that electrical stimulation is delivered using aparticular electrode combination. Thus, the minimum amplitude adjustmentincrements may be selected to increase or decrease the duration withwhich a particular electrode combination is tested on patient 12.Decreasing this value may increase the amount of time that a particularelectrode combination is tested on patient 12, which may increase theamount of time patient 12 has to provide input regarding the efficacy ofstimulation.

In some examples, the minimum amplitude adjustment increment and therate of change, are preset by a manufacturer or distributor ofprogrammer 18, IMD 14, or leads 16, and may not be modified by a usercontrolling the test electrical stimulation delivered to patient 12. Forexample, as described in further detail below with respect to FIGS.10A-10D, in some examples, processor 60 (or another processor) adjuststhe anodic and cathodic amplitudes in 10% amplitude increments, e.g., asdefined by the steps in a predefined schedule of amplitude adjustments.In other examples, the amplitude adjustment increments may be 5% stepsor 25% steps. In addition, for a particular predefined schedule, theamplitude adjustment increments may not all be the same size. Forexample, the amplitude adjustment increments could alternate between 4%and 6% as the steps propagate through the schedule.

In other examples, the minimum amplitude adjustment increment and therate of change may be modified by a user. For example, the user mayinteract with user interface 66 of programmer 18 to modify the amplitudeadjustment increments and/or the rate of change based on the particularpatient 12 to which electrical stimulation is being delivered. Variousfactors, such as the sensitivity of the patient and the implant site oflead 16A, may affect the extent to which a particular patient perceiveselectrical stimulation. As a result, different patients may finddifferent increment sizes to be comfortable. Thus, while electrodecombinations are automatically tested in example techniques describedherein, e.g., under the control of programmer 18, IMD 14, or both), someaspects of the electrode testing may be manually changed by a clinician.

After selecting the next electrode combination to test, processor 60controls IMD 14 to deliver electrical stimulation with the selectedelectrode combination (80), determines whether user input has beenreceived (82), and so forth until there are no further electrodecombinations to test (“NO” branch of block 86).

In response to determining there are no additional electrodecombinations to test (“NO” branch of block 86), the delivery ofelectrical stimulation via the set of electrode combinations in thepredetermined order ends. In some examples, after processor 60 ends theelectrical combination identification process, processor 60 generatesand displays a list of the tested electrode combinations (e.g., theelectrode combinations from the plurality of predetermined electrodecombinations) for viewing by the clinician. The list can include, forexample, graphical representations of the electrode combinations, namesof the electrode combinations, or any other identifiers. Efficacyinformation associated with the electrode combinations, e.g., receivedby processor 60, may also be presented to the clinician (or other user).In this manner, programmer 18 may present information to the clinician(or other user) that informs the identification of an efficaciouselectrode combination for patient 12.

For example, the efficacy information may be displayed alongside theassociated electrode combination identifier, or the user interfacegenerated by processor 60 may be dynamic and a user may interact withthe user interface to select an electrode combination from the list,and, in response to receiving the user input, processor 60 can retrievethe efficacy information associated with the selected electrodecombination, e.g., from memory 62, and display the efficacy informationvia a display of user interface 66. In some examples, processor 60 mayorder the list of tested electrode combinations based on the efficacyinformation, e.g., an ascending or descending order of efficacy ratings.

Processor 60 of programmer 18, automatically or with the aid of aclinician, may select one or more of the tested electrode combinationsbased on the results of the electrical stimulation delivery via theplurality of test electrode combinations. Processor 60 may, for example,select one or more of the electrode combinations and create one or moretherapy programs (including the selected electrode combinations) forprogramming IMD 14 for chronic therapy delivery or for further testing,or take any other suitable action.

In some examples, processor 60 of programmer 18, automatically or withthe aid of a clinician, may select additional electrode combinations totest on patient 12 based on the results of the electrical stimulationdelivery via the plurality of test electrode combinations. Processor 60may select the additional electrode combinations to test on patient 12using any suitable technique. In some examples, processor 60 selectselectrode combinations, e.g., associated with the highest efficacyratings, from the plurality of tested electrode combinations, and theselected electrode combinations can be used to determine additionalcombinations to test, e.g., using an electrode combination searchalgorithm, a table, or another technique.

An example search algorithm is described in U.S. Patent ApplicationPublication No. 2005/0060009 by Goetz et al., which is entitled,“SELECTION OF NEUROSTIMULATOR PARAMETER CONFIGURATIONS USING GENETICALGORITHMS” and published on Mar. 17, 2005. U.S. Patent ApplicationPublication No. 2005/0060009 by Goetz et al. describes devices, systems,and techniques for selection of parameter configurations, includingelectrode combinations, using genetic algorithms, which may provideguidance in the electrode combination selection process, interactivelyguiding the clinician by suggesting electrode combination that are mostlikely to be efficacious given the results of tests already performedduring an evaluation session (e.g., tests performed using the set ofelectrode combinations). U.S. Patent Application Publication No.2005/0060009 by Goetz et al. is incorporated herein by reference in itsentirety.

As another example of how additional electrode combinations to test onpatient 12 may be selected, processor 60 may select one or more of theelectrode combinations from the set of tested electrode combinations,and the selected one or more electrode combinations may indicate thatcertain other electrode combinations may be efficacious. For example, aselected electrode combination may be associated with one or moreadditional electrode combinations in a table stored by memory 62 (oranother memory, such as memory 32 of IMD 14). The one or more additionalelectrode combinations can be, for example, electrode combinations thatmay result in similar therapy fields as the one or more electrodecombinations selected from the set, or electrode combinations that areknown to result in similar efficacy based on historical data fromanother patient or class of patients. A therapy field can be, forexample, an electrical field model that is generated based upon apatient anatomy data (specific to patient 12 or generic to multiplepatients) and a therapy program defining stimulation parameter values(including an electrode combination), where the electrical field modelrepresents the areas of a patient anatomical region that will be coveredby an electrical field during therapy delivery via the associatedelectrode combination.

FIG. 4B is a flow diagram of another example technique for identifyingone or more electrode combinations that may provide efficacious therapyfor patient 12. In the technique shown in FIG. 4B, processor 30, e.g.,under the control of processor 60 of programmer 18, controls stimulationgenerator 34 to deliver electrical stimulation therapy to patient 12according to a predefined schedule of amplitude adjustments (89). Thepredefined schedule of amplitude adjustments defines the set ofelectrode combinations to be automatically tested on patient 12, e.g.,during a programming session. The predefined schedule of amplitudeadjustments may be stored by memory 62 of programmer 18, memory 32 ofIMD 14, or a memory of another device (e.g., a cloud memory device).

The predefined schedule of amplitude adjustments includes a plurality ofsteps and, for each step, the active electrodes used for delivery ofelectrical stimulation therapy, and, for each of the active electrodes,the anodic and cathodic amplitude settings. Each “step” may represent,for example, a time slot, such that subsequent steps are taken insubsequent slots of time. In some examples, the time slot is predefined,and may be, for example, 200 milliseconds (ms) to about 1 second. Duringa particular time slot, an electrode combination (defined by the activeelectrodes) and respective anodic and cathodic amplitude settings withwhich IMD 14 delivers electrical stimulation to patient 12 remainssubstantially the same (e.g., nearly the same or the same).

In some examples in which stimulation generator 34 and stimulationgenerator 34 include a plurality of stimulation engines, processor 30may determine an absolute current amplitude value for the electrodecombination, a percentage contribution of the absolute current amplitudefor each anode in the electrode combination (the anodic amplitude), andan effective amplitude for each cathode in the electrode combination(the cathodic amplitude). Processor 60 may control stimulation generator34 to incrementally increase or decrease the anodic amplitude andcathodic amplitudes (based on the amplitude settings defined by theschedule) in any suitable amplitude adjustment increments, which can be,but need not be, the same for all of the steps of the schedule. Forexample, the amplitude adjustment increments may be defined as a percentchange, and the anodic and/or cathodic amplitude may be, modified (e.g.,increased or decreased) by processor 60 in any suitable percentageincrements, such as about 4%, 5%, 6%, 10%, or 25% increments. While thetotal amplitude of the electrical stimulation may not change with theamplitude adjustments, the distribution of the amplitude between theanodes and/or between the cathodes changes with each amplitudeadjustment defined by the schedule.

The amplitude adjustment increments may be selected to minimize theperception of the electrode combination transition by patient 12. Insome examples, the schedule defines cathodic amplitude settings asamplitude values, such that the minimum amplitude adjustment incrementfor a cathodic amplitude may be defined in terms of amplitude value. Insome examples, the minimum amplitude adjustments can be about 1/64 of0.1 milliamps (mA), such as about 1 microamp (μA), to about 0.1 mA. Inaddition, in some examples, the schedule defines anodic amplitudesettings as a percentage of total current, such that the minimumamplitude adjustment increment for anodic amplitude may be defined interms of a percentage increment. In one example, the percentageincrements may be, for example, about 4% to about 6% each.

In some examples, stimulation generator 34 adjusts the anodic andcathodic amplitudes using the same amplitude adjustment increments. Inother examples, the stimulation generator 34 adjusts the anodic andcathodic amplitudes using different amplitude adjustment increments. Insome examples, the schedule may define the amplitude adjustmentincrements, e.g., by defining the anodic and cathodic amplitudes foreach step.

The technique shown in FIG. 4B is similar to the technique describedwith respect to FIG. 4A, but instead of determining whether there areadditional electrode combinations to test (86) and selecting the nextelectrode combination to test (88), processor 60 automatically selects anext electrode combination in the set to test as a result ofincrementally adjusting anodic and/or cathodic currents in accordancewith a predefined schedule of amplitude adjustments. A shift betweenadjacent electrode combinations in the predefined set (referred toherein as “first” and “second” electrode combinations for ease ofdescription) may occur due to the incremental amplitude adjustmentdefined by a step of the schedule.

As described in further detail with respect to FIGS. 10A-11D, processor30 may control stimulation generator 34 to shift between first andsecond electrode combinations, in accordance with the schedule, by atleast incrementally decreasing the current amplitude sunk by cathodes ofa first electrode combination that are not shared by the secondelectrode combination, and incrementally increasing the currentamplitude sunk by the cathodes of the second electrode combination thatare not shared with the first electrode combination until only cathodesof the second electrode combination are active. If the second electrodecombination includes at least one more cathode than the first electrodecombination, then stimulation generator 34 may incrementally decreasethe current amplitude sunk by cathodes shared by the first and secondelectrode combinations as stimulation generator 34 incrementallydecreases the current amplitude sunk by the other cathodes of the firstelectrode combination and incrementally increases the current amplitudesunk by the other cathodes of the second electrode combination. If thesecond electrode combination includes at least one fewer cathode thanthe first electrode combination, then stimulation generator 34 mayincrementally increase the current amplitude sunk by cathodes shared bythe first and second electrode combinations as stimulation generator 34incrementally decreases the current amplitude sunk by the other cathodesof the first electrode combination and incrementally increases thecurrent amplitude sunk by the other cathodes of the second electrodecombination.

In some examples, processor 30 may control stimulation generator 34 toshift between first and second electrode combinations, in accordancewith the schedule, by at least incrementally decreasing a percentage ofcurrent assigned to (e.g., sourced by) anodes of the first electrodecombination that do not overlap with the second electrode combination,and incrementally increasing a percentage of current assigned to anodesof the second electrode combination that do not overlap with the firstelectrode combination until only anodes of the second electrodecombination are active. If the second electrode combination includes atleast one more anode than the first electrode combination, thenstimulation generator 34 may incrementally decrease the percentage ofcurrent assigned to anodes shared by the first and second electrodecombinations as stimulation generator 34 incrementally decreases thepercentage of current assigned to the other anodes of the firstelectrode combination and incrementally increases the percentage ofcurrent assigned to other anodes of the second electrode combination. Ifthe second electrode combination includes at least one fewer anode thanthe first electrode combination, then stimulation generator 34 mayincrementally increase the percentage of current assigned to anodesshared by the first and second electrode combinations as stimulationgenerator 34 incrementally decreases the percentage of current assignedto the other anodes of the first electrode combination and incrementallyincreases the percentage of current assigned to other anodes of thesecond electrode combination.

The transition between the first and second electrode combinations inthe predefined set may occur once only cathodes and anodes of the secondelectrode combination are active. The amplitude adjustment settings andsteps of the schedule may define the rate of transition betweenelectrode combinations. In some examples, a clinician may provide inputto processor 60 via user interface 66 to modify the amplitude adjustmentincrements (e.g., select an increment within a preset range), which may,in turn, affect the rate of transition between electrode combinations.Thus, in some examples, the testing of a set of electrode combinationsmay be automated by programmer 18, but certain aspects of the testingmay be controlled by a user.

As shown in the example of FIG. 4B, if processor 60 has not receiveduser input (“NO” branch of block 82) or after taking a responsive action(84), processor 60 may determine whether the schedule defines anyadditional (anodic and cathodic) amplitude adjustments to be made (90).For example, processor 60 may determine whether the schedule includesany steps that have not been completed yet. In response to determiningthere are additional amplitude adjustments to be made (“YES” branch ofblock 90), processor 60 may continue controlling IMD 14 to deliverelectrical stimulation to patient 12 with the electrode combinations andrespective anodic and cathodic amplitudes defined by the predefinedschedule (80). In response to determining there are no additionalamplitude adjustments to implement (“NO” branch of block 90), processor60 may terminate the automatic testing of the predefined set ofelectrode combinations.

FIG. 6 is a table illustrating an example set of test electrodecombinations that may be used to identify one or more efficaciouselectrode combinations for patient 12 in accordance with some exampletechniques described herein. As discussed in further detail below, theset of test electrode combinations are arranged in a predetermined orderthat has been determined to result in efficient transitions betweenadjacent electrode combinations. The set of test electrode combinationsshown in FIG. 6 may be stored by memory 32 of IMD 14, memory 62 ofprogrammer 18, or a memory of another device.

Electrodes 24 of lead 16A are shown in the first column of the tableshown in FIG. 6, and the other columns indicate electrode combinations.The top row shown in FIG. 6 includes identifiers for the electrodecombinations, i.e., “A,” “B,” and so forth through “EE.” Thealpha-identifiers shown in FIG. 6 are merely an example of anidentifier, and any suitable identifier, whether any combination ofalphabetical, numeric, graphical, and the like, may be associated withstored electrode combinations and used to identify the stored electrodecombination. Each of the other rows in the table shown in FIG. 6corresponds to a respective electrode. For each electrode combinationA-EE, a symbol, “+” (indicating an anode) or “−” (indicating a cathode)in the row corresponding to the electrode indicates the electrode isactive and included in the electrode combination. For example, as shownin FIG. 6, electrode combination A includes electrodes 24A, 24B, whereelectrode 24A serves as a cathode and electrode 24B serves as an anode.

In some example techniques for identifying one or more efficaciouselectrode combinations, processor 60 of programmer 18 or processor 30 ofIMD 14 or another device controls stimulation generator 34 (FIG. 2) ofIMD 14 to generate and deliver electrical stimulation to patient 12 viaeach of electrode combinations A-EE shown in FIG. 6. Scanning througheach of electrode combinations A-EE may take, for example, less thanfive minutes, such as about three minutes, if the scanning isuninterrupted. A technique in which processor 60 of programmer 18controls stimulation generator 34 is described with reference to FIG. 6.In other examples, however, processor 30 of IMD 14 or another device mayperform any part of the technique described herein.

Processor 60 is configured to control stimulation generator 34 togenerate and deliver electrical stimulation to patient 12 via each ofelectrode combinations A-EE at different times. For example, processor60 may transmit control signals to IMD 14 that cause stimulationgenerator 34 (e.g., under the control of processor 30) to generate anddeliver electrical stimulation via electrode combination A, and,subsequently, terminate the delivery of electrical stimulation viaelectrode combination A and deliver electrical stimulation via electrodecombination B, and, subsequently, deliver electrical stimulation viaelectrode combination A, and, subsequently, terminate the delivery ofelectrical stimulation via electrode combination B and deliverelectrical stimulation via electrode combination C, and so forth untileach of electrode combinations A-EE has been tested. As described withrespect to FIGS. 10A-11D, the transitions between electrode combinationsA-EE may be relatively subtle due to the manner in which the cathodicand anodic amplitudes may be adjusted to transition between electrodecombinations.

In some examples, stimulation generator 34 may generate the electricalstimulation signal delivered via each of the electrode combinations A-EEwith a common set of other stimulation parameter values (e.g., currentor voltage amplitude and frequency). In this way, the variable that ischanging may be limited to the electrodes with which electricalstimulation is delivered to patient 12. In other examples, however,stimulation generator 34 may generate the electrical stimulation signaldelivered via at least two of the electrode combinations A-EE withdifferent stimulation parameter values. Different stimulation parametervalues may be selected if, for example, one set of other stimulationparameter values would result in uncomfortable stimulation for one ormore of the electrode combinations due to the relative position betweenthe electrodes of the electrode combination and the tissue of patient12.

In accordance with an example automated electrode combination testingtechnique, under the control of processor 60, stimulation generator 34may generate and deliver electrical stimulation therapy to patient 12via electrode combination A. Under the control of processor 60,stimulation generator 34 may, for example, initiate electricalstimulation via electrode combination A by assigning 100% of theamplitude to cathode electrode 24A and 100% of the amplitude to anodeelectrode 24B. Stimulation generator 34 may deliver electricalstimulation via electrode combination A for a predetermined period oftime sufficient for patient 12 to feel the effects of the electricalstimulation. The predetermined period of time during which IMD 14delivers electrical stimulation to patient 12 via a particular electrodecombination may be referred to as a “test period.”

The duration of the test period may differ between patients, based onclinician preference, or based on other factors. In addition, theduration of the test period may depend on the number of anodic andcathodic amplitude adjustment increments between adjacent electrodecombinations. In some examples, the test period may be 0.2 seconds toabout 10 seconds. Within a test period for a particular electrodecombination, stimulation generator 34 may change the anodic and cathodicamplitudes. Depending on the amplitude adjustment increments,stimulation generator 34 may deliver electrical stimulation to patient12 according to a particular electrode combination and particular anodicand cathodic amplitude setting for about 200 ms to about 1 second. Thistime period may be a predetermined period of time sufficient for patient12 to feel the effects of the electrical stimulation.

In some examples, the test period may be extended, e.g., if theautomatic scanning implemented by programmer 18 is paused by a clinicianand the electrical stimulation according to a particular electrodecombination is maintained while a user adjusts one or more stimulationparameter values, e.g., as discussed above with respect to FIGS. 4A and4B, and in further detail below with respect to FIG. 12.

After the test period for electrode combination A, under the control ofprocessor 30, stimulation generator 34 may generate and deliverelectrical stimulation therapy to patient 12 via electrode combination Bfor a test period. Stimulation generator 34 may shift from electrodecombination A to electrode combination B using any of the techniquesdescribed herein. As shown in FIG. 6, cathode electrode 24A and anodeelectrode 24B are shared by (common to) electrode combinations A and B.However, electrode combination B includes another anode electrode 24C.Thus, in one example, processor 30 controls stimulation generator 34 togradually increase the amplitude sourced by anode electrode 24C, e.g.,in predetermined minimum amplitude increments, while graduallydecreasing the amplitude applied to anode electrode 24B. The delivery ofelectrical stimulation is transitioned from electrode combination A toelectrode combination B at the point in time at which anode electrode24C was activated.

Similarly, as described with respect to FIGS. 10A-11D, stimulationgenerator 34 may continue to gradually increase the amplitude sourced byanode electrode 24C, while gradually decreasing the amplitude applied toanode electrode 24B until anode electrode 24B is deactivated. At thistime, the shift from electrode combination B to electrode combination Cis complete. During the increasing of the anodic current assigned toanode electrode 24C and the decreasing of the anodic current assigned toanode electrode 24C, electrode combination B is being tested on patient12.

Processor 30 or processor 60 controls the order in which the electrodecombinations A-EE are selected and tested on patient 12 based on thepredetermined order in which the electrode combinations are stored andarranged in the table shown in FIG. 6. Thus, in the example shown inFIG. 6, after delivering electrical stimulation therapy to patient 12via electrode combination B for a test period, stimulation generator 34may generate and deliver electrical stimulation therapy to patient 12via electrode combination C for a test period. After deliveringelectrical stimulation therapy to patient 12 via electrode combination Cfor a test period, stimulation generator 34 may generate and deliverelectrical stimulation therapy to patient 12 via electrode combination Dfor a test period, followed by electrode combination E for a testperiod, and so forth until stimulation generator 34 delivers electricalstimulation to patient 12 via each of electrode combinations A-EE shownin FIG. 6.

The test periods during which electrode combinations A-EE are eachtested may be substantially the same (e.g., the same or nearly the same)or different, which may depend on the increments with which the anodicand cathodic amplitudes are adjusted, as discussed above and/or whetheruser input interrupting the delivery of stimulation is received byprocessor 60 of programmer 18. The user input may cause a test period tobe restarted in some examples.

The electrode combinations in the set shown in FIG. 6 are arranged todefine a sequence of major electrode patterns, which, in the exampleshown in FIG. 6, are the four electrode patterns shown in FIGS. 5A-5D.Each of the electrode patterns shown in FIGS. 5A-5D appear at multipletimes at different positions in the sequence. For example, the simplebipole shown in FIG. 5A is used to define electrode combinations A, E,I, M, Q, and Y. In this way, the major electrode patterns are tested atdifferent axial positions along lead 16A, which may increase therobustness of the process for identifying an efficacious electrodecombination for patient 12.

In addition, the electrode combinations in the set shown in FIG. 6include minor electrode patterns. For example, electrode combination Bincludes two anodes 24B, 24C, which is an electrode pattern that resultswhen stimulation generator 34 is transitioning from delivery ofelectrical stimulation via electrode combination A to delivery ofelectrical stimulation via electrode combination C. Other minorelectrode patterns that appear in the set of electrode combinationsshown in FIG. 6 include electrode combinations D, X, BB, and DD.

The electrode patterns are arranged in the sequence such that thetransition between subsequently tested electrode combinations is logicaland efficient. In some examples, the logic and efficiency is at leastpartially attributable to the arrangement of electrode combinations inthe set such that adjacent electrode combinations include at least oneanode electrode or cathode electrodes. For example, electrodecombination K includes anode electrode 24B and cathode electrode 24Cfrom immediately preceding electrode combination J. As another example,electrode combination T includes anode electrode 24D and cathodeelectrode 24E from immediately preceding electrode combination S.Sharing at least one anode or cathode electrode with a prior-testedelectrode combination may reduce the amount of time required togradually modify amplitude delivered via a particular electrode.

As discussed above, in some examples, a plurality of electrodecombinations in a set to be tested on patient 12 may be arranged in apredetermined order such that the electrode combinations move throughthe levels of electrodes 24 (e.g., “walked” down lead 16A). For example,when electrode combinations A-EE are selected in the predetermined ordershown in FIG. 6, the electrodes with which electrical stimulation isdelivered to patient 12 move distally down lead 16A (where electrode 24His a distal-most electrode). For at least some electrode combinations, adistal-most electrode (e.g., the electrode closest to a distal end oflead 16A) is more distal (e.g., closer to a distal end of lead 16A) thanthe proximal-most electrode of the previous electrode combination in theset. For example, in the set of electrode combinations shown in FIG. 6,a distal-most electrode of electrode combination B is electrode 24C,which is closer to a distal end of lead 16B than proximal-most electrode24A of electrode combination B.

As another example of how electrode combinations may be ordered to movethrough the levels of electrodes 24, the electrode combinations may beordered such that, with the exception of the first two electrodecombinations, a distal-most electrode of a particular electrodecombination (referred to as a “first” electrode combination for ease ofdescription) is closer to a distal end of lead 16A than theproximal-most electrode of a preceding electrode combination (referredto as a “second” electrode combination for ease of description) that isseparated (in the order) from the first electrode combination by one ormore electrode combinations. For example, in the set of electrodecombinations shown in FIG. 6, a distal-most electrode 24E of electrodecombination L is closer to a distal end of lead 16A than proximal-mostelectrode 24B of electrode combination J (which precedes combination Lin the order and is separated from combination L by at least oneelectrode combination).

IMD 14, programmer 18, or another device may store a set of electrodecombinations (e.g., the set shown in FIG. 6 including electrodecombination A-EE) for automatically testing on patient 12 in order toidentify an efficacious electrode combination for patient 12. In someexamples, IMD 14, e.g., independently or under the control of programmer18 or another device, automatically delivers electrical stimulation topatient 12 according to each electrode combination of the set and a usermay not modify the electrode combinations in the set. This may be, forexample, because a clinician has determined that it is valuable to testeach electrode combination in the set on patient 12 in order to bethorough. In other examples, however, as discussed above with respect toFIGS. 4A and 4B, a user may modify the electrode combinations in theset, e.g., by eliminating certain electrode combinations. A clinicianmay, for example, eliminate electrode combinations that includeelectrodes that the clinician has determined are not proximate a targettissue site in patient 12, and, therefore, may not result in efficacioustherapy delivery to patient 12.

A user may modify electrode combinations in the set using any suitabletechnique. For example, programmer 18 may generate a display that liststhe electrode combinations in the set and a clinician may, with the aidof user interface 66 (FIG. 3), manually select and remove electrodecombinations from the set by identifying the electrode combinations bythe associated identifier (e.g., “A,” “B”, etc.). In addition, orinstead, programmer 18 may generate a display that lists the electrodepatterns that are used to define the electrode combination, and aclinician may, with the aid of user interface 66 (FIG. 3), manuallyselect and remove electrode patterns being tested by identifying theelectrode combinations by the associated identifier (e.g., “A,” “B”,etc.). In response to receiving such user input, processor 60 ofprogrammer 18 (or another processor, such as processor 30 of IMD 14) maydetermine which electrode combinations of the set include the electrodepattern and eliminate the determined electrode combinations from theset. For example, in response to receiving user input that indicates aguarded double cathode should be removed from the set of electrodecombinations being tested on patient 12, processor 60 may eliminateelectrode combinations H, L, P, and T from the set of electrodecombinations to be tested on patient 12.

In addition, or instead of the examples discussed above, a user mayeliminate electrode combinations in the set by interacting with userinterface 66 to provide select a starting electrode for the testingprocess. The starting electrode may be, for example, a proximal-mostcathode electrode for the first electrode combination (or a distal-mostcathode electrode, depending on the order in which electrodecombinations are “walked” down lead 16A). In response to receiving theuser input, processor 60 of programmer 18 (or another processor, such asprocessor 30 of IMD 14) may determine which electrode combinations ofthe set include proximal-most cathode electrode (or distal-most cathodeelectrode in other examples) and skip to that part of the set. Forexample, in response to receiving user input that indicates theelectrode testing should start with electrode 24C as the proximal-mostcathode, and the electrode combinations are walked down lead 16A towardthe distal end of lead 16A, processor 60 may begin the testing atelectrode combination I.

In addition, or instead of the examples discussed above, a user mayeliminate electrode combinations in the set by interacting with userinterface 66 to provide select an ending electrode for the testingprocess. The ending electrode may be, for example, a distal-mostelectrode (e.g., cathode electrode) for the first electrode combination(or a proximal-most electrode, depending on the order in which electrodecombinations are “walked” down lead 16A). In response to receiving theuser input, processor 60 of programmer 18 (or another processor, such asprocessor 30 of IMD 14) may determine which electrode combinations ofthe set include distal-most electrodes (or distal-most electrode inother examples) that are distal to the electrode selected by the userand eliminate the determined electrode combinations from the set. Forexample, in response to receiving user input that indicates theelectrode testing should end at electrode 24G and the electrodecombinations are walked down lead 16A toward the distal end of lead 16A,processor 60 may eliminate electrode combinations BB-EE from the set ofelectrode combinations to be tested on patient 12. The testing ofelectrical combinations may be driven by cathodes, so, in some examples,in response to receiving user input indicating the user wants to end thetesting at electrode 24G, processor 60 ends the testing with theelectrode combination in the set having electrode 24G as a distal-mostcathode.

Combinations that include anode electrodes distal to electrode 24G maystill be tested in response to the user input indicating 24G should bethe last cathode electrode tested. One exception, however, maybe ifprocessor 60 determines, e.g., based on a measured impedance greaterthan a threshold value, that the electrical pathway including electrode24H (or another electrode) has an open circuit condition. In this case,processor 60 may automatically skip every electrode combination thatincludes that high impedance electrode as an active electrode. Processor60 may, in some examples, notify a user via user interface 66 that theelectrode combinations were skipped, that a particular electrode hasbeen identified as exhibiting a high impedance, or both.

In addition, or instead of the examples discussed above, a user maydetermine that skipping an area of stimulation is desirable. Thus, theuser may provide input to, for example, eliminate a particular electrode24C from the electrode combinations being tested. For example, if theuser indicates electrode 24C should be eliminated because it does notprovide a desirable outcome when programmed as a cathode, processor 60can skip electrode combinations H-L from the predefined set of electrodecombinations. In any of these examples in which electrode combinationsare skipped, processor 60 may control stimulation generator 34 togradually apply the next electrode combination in the step, e.g., usingthe techniques to ramp up or ramp down anodic and cathodic amplitudesdescribed herein. For example, processor 60 may control stimulationgenerator 34 to ramp down electrical stimulation applied via oneelectrode combination to a zero amplitude (or as close to zero as thehardware permits) prior to ramping up electrical stimulation applied viathe next electrode combination selected based on the user input. Thistechnique may help minimize any sudden changes in electrical stimulationthat may be uncomfortable to patient 12.

Other techniques may be used to modify the electrode combinations of apredetermined set of electrode combinations to be tested on patient 12.In some examples in which the electrode combinations in the set areordered such that the electrode combinations move through the levels ofelectrodes 24 (e.g., “walked” down lead 16A) in a common direction, themodification to the electrode combinations of the set of electrodecombinations does not change the general order of electrodecombinations, such that the modified set also includes electrodecombinations arranged in order such that the electrode combinations movethrough the levels of electrodes.

In some examples, system 10 may be configured to enable the user tomodify electrode combinations in the set at any suitable time. Forexample, programmer 18 can be configured to enable the user to modifyelectrode combinations in the set prior to initiating the test therapydelivery according to the set of test electrode combinations. Inaddition, or instead, a user may modify electrode combinations in theset during the test therapy delivery according to the set of testelectrode combinations. For example, the user may pause the automaticscanning any time after initiating the test therapy delivery accordingto the set of test electrode combinations, eliminate some electrodecombinations, and then control IMD 14 to resume delivery of the testelectrical stimulation via the remaining electrode combinations in theset.

While lead 16A including one column of eight electrodes is primarilyreferred to throughout the description of the electrode combinationidentification techniques described above, the techniques describedherein may also be used to identify one or more efficacious electrodecombinations that include a subset of electrodes of a lead having agreater or a fewer number of electrodes, or even two or more columns ofelectrodes.

In another example, a set of electrode combinations includes onlyelectrode combinations in which the anode and cathode electrodes areprogrammed together on adjacent electrodes without any inactiveelectrodes between the active electrodes. This type of arrangement ofanode and cathode electrodes may minimize the area of activation of theneurons as the electrode combinations propagate down the electrodearray. Thus, in some examples, a predefined set of electrodecombinations is similar to that shown in FIG. 6, but does not includeelectrode combinations C and CC.

FIGS. 7-9 are tables illustrating example sets of test electrodecombinations that may be used to identify one or more efficaciouselectrode combinations for patient 12 in accordance with some exampletechniques described herein. The set of test electrode combinationsshown in FIG. 7 may be used to identify one or more efficaciouselectrode combinations that include a subset of electrodes of a leadhaving six electrodes, i.e., electrodes E0-E5, where electrode E5 may becloser to a distal end of the lead than electrode E0 or vice versa. Theset of test electrode combinations shown in FIG. 8 may be used toidentify one or more efficacious electrode combinations that include asubset of electrodes of a lead having four electrodes, i.e., electrodesE0-E3, where electrode E3 may be closer to a distal end of the lead thanelectrode E0 or vice versa. The set of test electrode combinations shownin FIG. 9 may be used to identify one or more efficacious electrodecombinations that include a subset of electrodes of a lead having fiveelectrodes, i.e., electrodes E0-E4, where electrode E4 may be closer toa distal end of the lead than electrode E0 or vice versa.

The electrode combinations in each of the sets of test electrodecombinations shown in FIGS. 7-9 are arranged to define a sequence ofmajor electrode patterns, which are the four electrode patterns shown inFIGS. 5A-5D. In addition, as with the set of electrode combinationsshown in FIG. 6, the electrode combinations in the sets shown in FIGS.7-9 include minor electrode patterns.

As with the set of test electrode combinations shown in FIG. 6, each ofthe sets of test electrode combinations shown in FIGS. 7-9 are arrangedin a predetermined order that has been determined to result in efficienttransitions between adjacent electrode combinations. For example, withineach set, adjacent electrode combination includes at least one sharedanode electrode or cathode electrode. In addition, within each set, theorder of electrode combinations results in electrode combinations beingwalked down the lead (e.g., from a proximal end to a distal end, or viceversa).

Other sets of electrode combinations are contemplated and may depend onthe electrode patterns that are selected to be tested on patient, thenumber of electrodes available for defining the electrode combinations,and the like.

In some examples, the anodic amplitudes and cathodic amplitudes areadjusted in a predetermined manner as the electrode combinations of apredefined set are tested in a predetermined order. The predeterminedmanner may be selected such that one or more electrode combinations ofthe predefined set are delivered with different combinations of anodicand cathodic amplitudes. Processor 60 of programmer 18 (or anotherdevice, such as processor 30 of IMD 14) may control the adjustment tothe anodic amplitudes and cathodic amplitudes in a predetermined mannerusing a predefined schedule of amplitude adjustments, which defines theset of electrode combinations to be automatically tested on patient 12,e.g., during a programming session, which defines the set of electrodecombinations to be automatically tested on patient 12, e.g., during aprogramming session

FIGS. 10A-10D illustrate an example predefined schedule of amplitudeadjustments. The predefined schedule shown in FIGS. 10A-10D includes theelectrode combinations A-EE described with respect to FIG. 6. However,in addition to indicating which electrodes are active and the polarityof the electrodes, the schedule includes the anodic and cathodicamplitude settings for each time slot. The predefined schedule ofamplitude adjustments includes a plurality of steps, which are numberedin the leftmost column of the table shown in FIGS. 10A-10D, and, foreach step, the active electrodes used for delivery of electricalstimulation therapy, and, for each of the active electrodes, the anodicand cathodic amplitude settings. The settings are expressed in terms ofpercentages of total anodic amplitudes (shown as positive percentages)and cathodic amplitudes (shown as negative percentages).

Each “step” may represent, for example, a time slot. When implementingthe electrode testing process using the schedule shown in FIGS. 10A-10D,processor 60 may control stimulation generator 34 of IMD 14 (e.g.,directly or indirectly via instructions sent to processor 30 of IMD 14)to deliver electrical stimulation to patient 12 according to the activeelectrodes and amplitude settings of step 1, followed by step 2, and soforth until the end of the schedule is reached. At that time, theautomatic scanning through a predefined set of electrode combinationsmay be complete. Each step may represent a time slot, such that steps1-151 represent consecutive time slots. In some examples, the time slotis predefined, and may be, for example, 200 ms to about 1 second, andmay be adjusted by a user. During a particular time slot, the electrodecombination and respective anodic and cathodic amplitude settings withwhich IMD 14 delivers electrical stimulation to patient 12 remainssubstantially the same, as defined by the particular step.

As shown in FIG. 10A, for example, when implementing the electrodetesting process using the schedule shown in FIGS. 10A-10D, processor 30may control stimulation generator 34 of IMD 14 (e.g., directly orindirectly via instructions received from processor 60 of programmer 18)to begin the electrode combination testing process by deliveringelectrical stimulation to patient 12 according to electrode combinationA for a time slot, wherein 100% of the electrical stimulation current(or voltage if IMD 14 is a voltage controlled device) is sunk by cathodeelectrode 24A and 100% of the stimulation is sourced by anode electrode24B. In a next time slot, i.e., step 2, processor 30 controlsstimulation generator 34 to decrease the current sourced by anodeelectrode 24B by an increment of 10% of the total anodic amplitude, andincrease the current sourced by anode electrode 24C by an increment of10% of the total anodic amplitude, while the cathodic amplitude assignedto electrode 24A is held at 100%. This amplitude adjustment results in atransition from electrode combination A to electrode combination B.

In a next time slot, i.e., step 3, processor 30 controls stimulationgenerator 34 to decrease the current sourced by anode electrode 24B byanother increment of 10% of the total anodic amplitude, and increase thecurrent sourced by anode electrode 24C by another increment of 10% ofthe total anodic amplitude. This gradual modification to the anodicamplitude continues, and, as a result, at time slot 11, the electrodecombination is transitioned from electrode combination B to electrodecombination C. Steps 2-10 represent the test period for electrodecombination B.

The transition between adjacent electrode combinations is relativelysubtle (e.g., in perception by patient 12) due to the incrementalmodifications in anodic and/or cathodic amplitudes used to achieve thetransition. This may help minimize discomfort to patient 12 resultingfrom the transitions in electrode combinations.

As shown, a plurality of electrode combinations (i.e., electrodecombinations B-D, F, H, J-L, N, P, R, T, V, X, Z, BB, and DD) are testedusing a plurality of different anodic amplitude settings. The electrodecombinations and respective amplitude settings are shown as“sub-combinations” in the table of FIGS. 10A-10D, e.g., B1-B9. Theefficacy of electrical stimulation delivered via some electrodecombinations may change depending on the anodic and cathodic amplitudesettings. Thus, the schedule shown in FIGS. 10A-10D may be useful formore thoroughly evaluating an electrode combination compared totechniques in which every electrode combination is only tested at a oneanodic and cathodic amplitude setting. The electrode combinations A, E,G, I, M, O, Q, S, U, W, Y, AA, CC, and EE only have possible one anodicand cathodic amplitude setting (for a particular stimulation amplitude)because of the presence of only one anode electrode and one cathodeelectrode.

The schedule shown in FIGS. 10A-10D may be useful for efficientlyevaluating a plurality of electrode combinations at a plurality ofdifferent anodic and cathodic amplitude settings. When the scheduleshown in FIGS. 10A-10D or a similar schedule is stored and implementedby processor 60 (or processor 30) to test a predefined set of electrodecombinations on patient 12, the anodic and cathodic amplitude settingsand the timeline for modifying the anodic and cathodic amplitudesettings is also defined and arranged in a manner that results in anefficient use of time. This may help minimize or even eliminate theclinician control required to evaluate a plurality of electrodecombinations at a plurality of different anodic and cathodic amplitudesettings.

A predefined schedule of amplitude adjustments stored by IMD 14,programmer 18, or another device may define the anodic and cathodicamplitude settings using any suitable convention. In FIGS. 10A-10D, forexample, the settings are stored as percentages of the total anodicamplitude and total cathodic amplitude. FIGS. 11A-11D illustrate anotherexample predefined schedule of amplitude adjustments, which includes thesame electrode combinations and steps as FIGS. 10A-10D. However, inFIGS. 11A-11D, the anodic amplitude setting are expressed as apercentage of an absolute current amplitude, and a cathodic amplitudesettings are expressed as an amplitude at the respective cathode in theelectrode combination. Although FIGS. 10A-10D illustrate adjustmentincrements of 10%, in other examples, other amplitude adjustmentincrements may be used, such as increments of about 4% or 6%. Inaddition, although FIGS. 11A-11D illustrate amplitude adjustmentincrements of 10% and 0.5 mA, other amplitude adjustment increments maybe used.

Furthermore, the amplitude adjustment increments may be the same in eachstep of a predefined schedule in some examples, as shown in FIGS.10A-11D. In other examples, at least two steps different amplitudeadjustment increments. For example, the amplitude adjustment incrementsin FIGS. 10A-10D may alternate between 4% and 6% for subsequent steps inthe schedule.

In some examples, the electrode combination scanning process may betransparent to a user. For example, programmer 18 may be configured todisplay information identifying the current electrode combination beingtested on patient.

FIG. 12 is a schematic diagram illustrating an example GUI 91 that maybe generated and displayed by programmer 18. Processor 60 may generateand present GUI 91 in order to help a clinician identify one or moreefficacious electrode combinations, with which the clinician may defineone or more therapy programs. In the example shown in FIG. 12, processor60 of programmer 18 automatically selects the electrode combinations tobe tested on patient 12 and transmits information to IMD 14, e.g., viathe respective telemetry modules 64, 40, to control the delivery of teststimulation to patient 12 in accordance with the selected electrodecombination. For example, for each electrode combination of the settested on patient 12, processor 60 may transmit the parameters, e.g.amplitude, frequency, pulse width, and electrode combination, to IMD 14.In this manner, the order of electrode combinations can be stored on andmanaged by programmer 18, and not IMD 14. IMD 14 only receives definiteparameter values from programmer 18 according to which IMD 14 deliversstimulation to patient 12. In other examples, the order of electrodecombinations can be stored on and managed by processor 30 of IMD 14alone or in combination with programmer 18.

In the example of FIG. 12, programmer 18 comprises a touch screendisplay 92 that presents GUI 91, which includes a number of userinterface elements that represent leads and electrodes and electricalstimulation parameters. In some examples, as shown in FIG. 12, GUI 91includes a graphical representation of pair of leads 94, 96, eachincluding a set of eight electrodes. For example, a first lead 94includes electrodes 0-7 and a second lead 96 includes electrodes 8-15.Leads 94, 96 may be graphical representations of, for example, leads 16of system 10. The orientation of leads 94, 96 in GUI 91 is such that thedistal end of each lead is at the top of the display. GUI 91 mayschematically represents leads 94, 96 and respective electrodes as theygenerally are arranged implanted within patient 12, e.g., as twoside-by-side leads arranged vertically and each including a number ofelectrodes, e.g., eight electrodes.

In some examples, as a preliminary step to identifying one or moreefficacious electrode combinations, a user defines a lead configurationusing programmer 18. For example, the user can select a lead type andconfiguration from a list of options, e.g. a lead including four oreight ring electrodes. Once the lead type is selected, the user canselect the orientation of the lead on programmer display 92, e.g. orientthe lead vertically or horizontally on the display 92. In some cases, alead configuration including electrodes on two or three leads may beselected.

A user may interact with GUI 91 (e.g., by providing input using userinterface 66 of programmer 18) to select stimulation parameter valuesfor the test electrical stimulation and control the overall intensity ofthe stimulation delivered by IMD 14. For example, in the example shownin FIG. 12, GUI 91 includes an amplitude adjustment area 98, a pulsewidth adjustment area 100 and a frequency adjustment area 102. A usermay increase or decrease the intensity of the stimulations by selectingor entering parameter information within areas 98, 100, 102. Processor60 may control the stimulation parameters of the test stimulation energydelivered by IMD 14 based on the information within areas 98, 100, 102.As described above, in some examples, all or some of these stimulationparameters may be modified during the automatic testing of a set ofelectrode combinations, e.g., while the automatic testing is paused. Inother examples, all or some of these stimulation parameters may only bemodified before starting the automatic testing of the set of electrodecombinations, e.g., outside of the automatic testing programming featureprovided by programmer 18.

The amplitude displayed by area 98 may be, for example, an absolutecurrent amplitude for the test electrical stimulation. The intensity ofthe electrical stimulation energy may be a function of the amplitudedisplayed by area 98.

A user may also interact with GUI 91 to initiate the automatic scanthrough the electrode combinations of a set, e.g., to initiate theautomatic delivery of electrical stimulation by IMD 14 via electrodecombinations of the set. In some examples, programmer 18 is configuredto control IMD 14 to scan through (i.e., test) a plurality of differentsets of electrode combinations, and the user may interact with GUI 91 toselect a set of electrode combinations from the plurality of availablesets before initiating the automatic scan. In other examples, programmer18 is configured to control IMD 14 to automatically scan through asingle set of electrode combinations. In this case, the user may onlyneed to activate the programming tool in order to initiate the automaticscan.

In the example shown in FIG. 12, GUI 91 includes slow reverse button104, pause button 106, play button 108, and slow play button 110, whichmay be graphical objects displayed by processor 60 and selectable by auser. A user may initiate the automatic scan along the electrodes of alead 92 or 94 (or both leads 92, 94) by instructing programmer 18 toautomatically “play” through electrode combinations of the set in thepredefined order, according to a predefined schedule of amplitudeadjustments (if implemented), and according to the stimulationparameters indicated by areas 98, 100, 102. For example, the clinicianmay press a play button 108, and, in response to receiving such input,processor 60 may instruct IMD 14 to initiate stimulation according toeach electrode combination of the predefined set with the stimulationparameters selected by the clinician.

GUI 91 is configured to provide a number of controls for stopping ormodifying the automatic scan through the set of electrode combinations.For example, the user may activate pause button 106 to pause the scan atany point during the course of the automatic scan through the set ofelectrode combinations (in the predetermined order). In response toreceiving the input via pause button 106, processor 60 may instruct IMD14 to stop the delivery of electrical stimulation. In other examples, inresponse to receiving the input via pause button 106, processor 60 mayinstruct IMD 14 to maintain the delivery of electrical stimulation viathe currently selected electrode combination and anodic and cathodicamplitude settings, thereby stopping the changing of electrodecombination and anodic and cathodic amplitude settings at the point atwhich pause button 106 was selected, but not stopping the delivery ofelectrical stimulation. Thus, in some examples, after the user haspaused the scan, IMD 14 will continue to deliver stimulation to patient12, but will no longer continue to scan through the set of electrodecombinations.

While the automatic scan is paused, processor 60 is configured torestart the scan in response to receiving user input selecting playbutton 108 or selecting pause button 106 a second time. In response todetecting the re-initiation of the scan, processor 60 may instruct IMD14 to resume the scan. In examples in which electrical stimulation wasstopped in response to activation of the pause button 106, processor 60may instruct IMD 14 to resume delivering electrical stimulation topatient 12 via the last-selected electrode combination, e.g., byrestarting the time slot if the anodic and cathodic amplitude settingsare modified according to a predefined schedule defining a plurality oftime slots and associated anodic and cathodic amplitude settings. Inexamples in which electrical stimulation was maintained in response toactivation of the pause button 106, processor 60 may instruct IMD 14 tocontinue delivering electrical stimulation to patient 12 via thelast-selected electrode combination (and anodic and cathodic amplitudesettings) for a new time slot, continue delivering electricalstimulation to patient 12 via the last-selected electrode combinationfor the remainder of the time slot started prior to the pause, or toswitch to the next electrode combination in the order.

Processor 60 may also be configured to skip to a different electrodecombination in the set in response to receiving user input. For example,as discussed above, the user may pause a scan by selecting pause button106 and then select one of the displayed electrodes to select a newstarting electrode for the scan. In response to receiving inputselecting the new starting electrode, processor 60 may select adifferent electrode combination from the set, e.g., an electrodecombination having a proximal-most active electrode at the startingelectrode selected by the user, an electrode combination having aproximal-most cathode at the starting electrode, an electrodecombination having a proximal-most anode at the starting electrode, orthe like for distal-most positions.

As another example of how processor 60 may skip to a different electrodecombination in the set, in some examples, the user may reverse backwardsfrom the paused location through the set of electrode combinations inresponse to receiving input selecting skip backward button 104.Processor 60 may skip back one electrode combination in thepredetermined order for each selection of slow reverse button 104.Activation of the reverse function provided by programmer 18 requiresintervention by the user; that is, the reverse function is a manualprocess that requires the user to provide input to programmer 18, whichthen transmits commands to IMD 14. The reverse features of programmer 18may enable a clinician to quickly revisit an electrode combination andrespective anodic and cathodic amplitude settings, if desired.

Although not shown in FIG. 12, in some examples, GUI 91 also includes askip forward button, which may provide a similar function as slowreverse button 104, but permits the user to skip to an electrodecombination (and anodic and cathodic amplitude settings) at a laterposition in the order than the currently selected electrode combinationand anodic and cathodic amplitude settings combination. The skip forwardfeatures of programmer 18 may enable a clinician to skip the testing ofsome electrode combinations in the set, e.g., if the electrodecombinations are determined to be at axial positions of the lead thatare not proximate a target tissue site, and, therefore, may not resultin efficacious electrical stimulation, and/or skip some anodic andcathodic amplitude settings for a particular electrode combination.

Processor 60 may implement any suitable technique to transition betweena currently selected electrode combination and the electrode combinationto which the user wishes to skip forward or backward in the order. Forexample, processor 60 may transmit signals IMD 14 to cause stimulationgenerator 34 to reduce the electrical stimulation delivered via thestarting electrode combination down to zero and then ramp up thestimulation delivered to via the destination electrode combination upfrom zero to the programmed intensity, such that each electrodecombination is discretely selected and tested.

In the example shown in FIG. 12, GUI 91 also includes slow play button110, which enables the user to continue the scan in the predeterminedorder but at a slower speed. In response to receiving the user inputselecting button 110, processor 60 may change the rate at which thetransition between electrode combinations and/or anodic and cathodicamplitude settings take place. The slower speed of the scan may allowfor patient 12 to perceive the stimulation according to a particularelectrode combination and anodic and cathodic amplitude setting for alonger period of time, which may be useful for evaluating the efficacyof the electrode combinations. Processor 60 may change the rate oftransitions using any suitable technique, such as by adjusting theminimum amplitude adjustment increments or minimum percentageincrements, or increasing the duration of time period between theapplication of each of the increments (also referred to herein as timeslots). In some examples, processor 60 changes the rate of transitionsin response to user input. For example, processor 60 may generate andpresent a set-up screen prior to initiating the automatic scan through aset of electrode combinations, and the set-up screen may present theuser with options to set the speed of transitions between electrodecombinations, e.g., based on what may be comfortable for the particularpatient.

In each of the different user inputs described above that results inselection of a different electrode combination in the set, processor 60maintains the selection of the next electrode combination/amplitudeadjustment to test on patient 12 based on the predetermined order.Programmer 18 can be configured such that the user cannot modify theorder in which the electrode combinations are tested on patient 12. Inaddition, processor 60 may be configured to limit some user-specifiedmovements, such as movements that would lead to the overall output limitof IMD 12 being exceeded or if the movement would result in a relativelyhigh amount of electrical stimulation delivered to patient 12 via oneelectrode.

GUI 91 may include a stop button, a save & end button, or both, inaddition to or instead of slow reverse button 104, pause button 106,play button 108, and slow play button 110. The stop button may end thetesting of the set of electrode combinations, and the save & end buttonmay end the testing of the electrode combinations and save any input(e.g., user input marking one or more electrode combinations andassociated anodic and cathodic amplitude settings) received during thetesting. In either case, the stop button may permit the play button 108to be inactivated, and the user may provide input adjusting othersettings (e.g., adjusting the amplitude or other stimulation parametervalues).

In some examples, programmer 18 may be configured to receive user inputin another manner. For example, GUI 91 may not include one or more ofslow reverse button 104, pause button 106, play button 108, or slow playbutton 110. As another example, programmer 18 can include, as part ofGUI 91 or a physical input mechanism, other input devices, such as ascroll wheel.

Programmer 18 is configured to display information about the electrodecombination being tested on patient 12. For example, after the automaticscanning through electrode combinations of a set is initiated, processor60 may update the graphical representation of the electrodes of leads94, 96 to reflect the electrode combination with which IMD 14 iscurrently delivering electrical stimulation to patient 12. For example,processor 60 may update GUI 91 so that the active electrodes of theelectrode combination are associated with a polarity symbol, minus, “−,”for cathodes and plus, “+,” for anodes. The user may view this displayedgraphical representation of the electrode combination and quicklyascertain the electrode combination that is currently being tested onpatient 12.

Processor 60 may also present, via GUI 91, information about the anodicand cathodic amplitude settings, the intensity of the electricalstimulation energy being delivered via the displayed electrodecombinations, or both. In the example shown in FIG. 12, each activeelectrode of the electrode combination currently selected by processor60 is associated with a text box that includes a numerical valuerelating to the stimulation intensity with which the respectiveelectrode is programmed and/or is currently applying stimulation. Eachcathode electrode can be associated with a text box that indicates thestimulation amplitude value according to which that cathode isprogrammed and is currently applying stimulation to patient 12. In someexamples, each cathode electrode also includes a percentage thatreflects the current distribution to the electrode as a percentage ofthe total current delivered to all the cathodes of the electrodecombination.

Each anode electrode can be associated with a text box that indicates apercentage that reflects the current distribution to the electrode as apercentage of the total current delivered to all the anodes in theelectrode combination. The percentage current distribution for cathodesand anodes does not change as stimulation amplitude is ramped up ordown, e.g., based on user input provided via adjustment areas 98, 100,102. The amplitude of cathodes presented in the associated text boxes,however, can be a reflection of the actual stimulation current levelapplied and thus will increase or decrease with stimulation applied byIMD 14 via the respective electrode. The anodic and cathodic amplitudesettings indicated by the text boxes may illustrate, in real time, thetransition between subsequently tested electrode combinations.

As the intensity of electrical stimulation is increased or decreased,e.g., based on user input, during delivery of electrical stimulation byIMD 14 with the displayed electrode combination, the graphical displayof the active electrodes may change to reflect the state of the appliedstimulation. For example, processor 60 can update the amplitude in thetext box associated with a particular cathode of the electrodecombination to reflect the intensity of the stimulation currently beingapplied by IMD 14 via that cathode.

In some examples, processor 60 may also associate a graphic (not shownin FIG. 12) with the active electrodes, and modify the size of thegraphic as a function of the amplitude of the currently appliedstimulation. For example, as IMD 14 increases the stimulation applied topatient 12, processor 60 may modify GUI 91 to reflect the changingstimulation by increasing the size of the graphics representing therelative amplitudes of the stimulation currently applied via eachrespective electrode. The graphics can be, for example, circles oranother two dimensional graphics overlaying respective electrodes of theelectrode combination. The graphics may be another visual aid with whichthe user may quickly ascertain the electrode combination and anodic andcathodic amplitude settings being tested on patient 12.

In the example shown in FIG. 12, GUI 91 includes mark button 116, whichthe user may select to mark the electrical combination and associatedamplitudes currently displayed by GUI 91 and currently being used by IMD14 to deliver electrical stimulation to patient 12. Processor 60 mayreceive input via mark button 116 when a user determines that aparticular setting is efficacious. As discussed above, in response toreceive the input from user via mark button 116, processor 60 maygenerate a marker and associate the marker (e.g., in memory 62 oranother memory) with the electrode combination and, in some examples,the anodic and cathodic amplitude settings, implemented by IMD 14 at thetime the user provided the input. In some examples, processor 60 alsostores the other parameter values (indicated by inputs 98, 100, 102)with the marker and associated electrode combination. In this way, theuser can later retrieve the marked electrode combinations and determinethe stimulation parameter values that resulted in the efficaciouselectrode combination.

Although example electrode combination identification devices, systems,and techniques have been described with respect to selecting electrodecombinations of a single lead 16A having eight electrodes 24, in otherexamples, the devices, systems, and techniques described herein may beused to identify desirable combinations of electrodes within electrodesets that are configured in any way, and used to provide any type ofelectrical therapy. The electrode sets may include electrodes carried byone lead, two leads, or a device housing.

For example, if system 10 includes multiple columns of electrodes,whether on a single lead 16A or 16B or defined by two or more leads 16,a set of test electrode combinations can include electrode combinationsincluding electrodes from two or more columns of electrodes. As anotherexample, each of the electrode combinations of the set may includeelectrodes from a single column of electrodes, but the set of electrodecombinations may include test electrode combinations for two or morecolumns. In some examples, the electrode combinations may be ordered inthe set such that electrode combinations on a first column of electrodesare tested, followed by electrode combinations on a second column ofelectrodes (e.g., immediately adjacent to the first column).

For example, a set of test electrode combinations can include aplurality of electrode combinations that include electrodes from bothleads 16. Each electrode combination may only include electrodes fromone lead 16, and the electrode combinations can be arranged such thatelectrode combinations of a first lead 16A are scanned, followed by theelectrode combinations of a second lead 16B. In this example, theelectrode combinations may be arranged in a predetermined order suchthat adjacent electrode combinations share at least one anode electrodeor at least one cathode electrode, with the exception of adjacentelectrode combinations that include electrodes of different leads.

Electrode combinations including electrode combinations on both leads 16may also be part of a set of electrode combinations tested on patient12. Even in this example, electrode combinations of a predefined set maybe arranged in a predetermined order such that adjacent electrodecombinations share at least one anode electrode or at least one cathodeelectrode, and, in some examples, such that all electrode combinationsinclude adjacent active electrodes uninterrupted by inactive electrodes.

Although each of the sets of electrode combinations described hereinincludes multipolar electrode combinations (including both anode andcathode electrodes), in some examples, the devices, systems, andtechniques described herein may also be used to test a set of unipolarelectrode combinations on patient 12. The unipolar electrodecombinations may still be arranged such that adjacent electrodecombinations (e.g., defined by electrodes on a lead) share at least onecathode electrode.

The techniques described in this disclosure, including those attributedto IMD 14, programmer 18, or various constituent components, may beimplemented, at least in part, in hardware, software, firmware or anycombination thereof. For example, various aspects of the techniques maybe implemented within one or more processors, including one or moremicroprocessors, DSPs, ASICs, FPGAs, or any other equivalent integratedor discrete logic circuitry, as well as any combinations of suchcomponents, embodied in programmers, such as clinician or patientprogrammers, medical devices, or other devices.

For example, the electrode combination testing features describedherein, e.g., the control of delivery of electrical stimulation by IMD14 according to each electrode combination of a set of electrodecombinations in a predetermined order, may be embedded as a singlefunction within a full featured programmer 18. The programmer mayinclude the option to program parameters incorporating traditionalprogramming tools, as well as the diagnostic, measurement, and otherfeatures necessary to manage IMD 14. In other examples, the electrodecombination testing features could be deployed as a stand alone tool ina programmer 18. Moreover, the shifting process may be executed by IMD14 in response to instructions from programmer 18 during a programmingsession, in response to instructions from programmer 18 during ordinary,chronic usage of IMD 14 by patient 12, or in response to instructionsgenerated by processor 30 of IMD 14 itself.

In one or more examples, the functions described in this disclosure maybe implemented in hardware, software, firmware, or any combinationthereof. If implemented in software, the functions may be stored on, asone or more instructions or code, a computer-readable medium andexecuted by a hardware-based processing unit. Computer-readable mediamay include computer-readable storage media forming a tangible,non-transitory medium. The computer-readable medium may be acomputer-readable storage medium such as a storage device (e.g., a diskdrive, or an optical drive), memory (e.g., a Flash memory, read onlymemory (ROM), or random access memory (RAM)) or any other type ofvolatile or non-volatile memory that stores instructions (e.g., in theform of a computer program or other executable) to cause a programmableprocessor to perform the techniques described herein. Instructions maybe executed by one or more processors, such as one or more DSPs, ASICs,FPGAs, general purpose microprocessors, or other equivalent integratedor discrete logic circuitry. Accordingly, the term “processor,” as usedherein may refer to one or more of any of the foregoing structure or anyother structure suitable for implementation of the techniques describedherein.

In addition, in some aspects, the functionality described herein may beprovided within dedicated hardware and/or software modules. Depiction ofdifferent features as modules or units is intended to highlightdifferent functional aspects and does not necessarily imply that suchmodules or units must be realized by separate hardware or softwarecomponents. Rather, functionality associated with one or more modules orunits may be performed by separate hardware or software components, orintegrated within common or separate hardware or software components.Also, the techniques could be fully implemented in one or more circuitsor logic elements. The techniques of this disclosure may be implementedin a wide variety of devices or apparatuses, including an IMD, anexternal programmer, a combination of an IMD and external programmer, anintegrated circuit (IC) or a set of ICs, and/or discrete electricalcircuitry, residing in an IMD and/or external programmer.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method comprising: with one or more processors,selecting a predefined set of electrode combinations, wherein eachelectrode combination includes one or more anode electrodes, one or morecathode electrodes, or both one or more anode electrodes and one or morecathode electrodes, a relative arrangement of the one or more anodes andthe one or more cathodes defining an electrode pattern of the electrodecombination; and with the one or more processors, automaticallycontrolling a medical device to deliver, in a predetermined order,electrical stimulation to a patient via each electrode combination ofthe predefined set of electrode combinations, each pair of adjacentelectrode combinations in the predetermined order including at least onesame anode electrode or cathode electrode, wherein the electrodecombinations in the predetermined order define a predetermined sequenceof electrode patterns.
 2. The method of claim 1, further comprisingselecting an electrode combination from the predefined set of electrodecombinations based on the delivery of the electrical stimulation by themedical device.
 3. The method of claim 1, wherein at least one electrodepattern appears multiple times at different positions in the sequence.4. The method of claim 1, wherein the predetermined sequence ofelectrode patterns includes a repeating sequence of the electrodepatterns.
 5. The method of claim 1, wherein each pattern includes anodesand cathodes uninterrupted by inactive electrodes.
 6. The method ofclaim 1, wherein each pair of adjacent electrode combinations in thepredetermined order include at least one same anode electrode and atleast one same cathode electrode.
 7. The method of claim 1, wherein theelectrode combinations are defined by subsets of electrodes of anelectrical stimulation lead, wherein controlling the medical device todeliver, in the predetermined order, electrical stimulation to thepatient via each electrode combination of the predefined set ofelectrode combinations comprises controlling the medical device todeliver electrical stimulation to the patient via at least two electrodepatterns at two different axial positions along the lead.
 8. The methodof claim 1, wherein the electrode combinations are defined by subsets ofelectrodes of an electrical stimulation lead, wherein the electrodecombinations are arranged in the predetermined order such that electrodecombinations are propagated down the lead.
 9. The method of claim 1,further comprising: receiving a first user input; controlling themedical device to one of pause delivering electrical stimulation orcontinue delivering electrical stimulation according to a currentlyselected electrode combination of the predefined set of electrodecombinations in response to receiving the first user input; subsequentlyreceiving a second user input; and controlling the medical device totransition from the currently selected electrode combination to a nextelectrode combination in the predetermined order in response toreceiving the second user input.
 10. The method of claim 1, furthercomprising: receiving user input selecting a starting electrode;selecting a starting electrode combination from the predefined set ofelectrode combinations based on the starting electrode selected by theuser; and controlling the medical device to deliver electricalstimulation to the patient via the starting electrode combination andelectrode combinations of the predefined set of electrode combinationsfollowing the starting electrode combination in the predetermined order.11. The method of claim 1, further comprising: receiving user input; andmodifying the predefined set of electrode combinations in response toreceiving the user input.
 12. The method of claim 11, wherein modifyingthe predefined set of electrode combinations includes removing at leastone electrode combination from the predefined set of electrodecombinations.
 13. The method of claim 1, wherein the electrode patternsinclude a first simple bipole, a second simple bipole, a guardedcathode, and a guarded double cathode.
 14. The method of claim 1,wherein controlling the medical device to deliver electrical stimulationto the patient via the predefined set of electrode combinations in thepredetermined order comprises controlling the medical device totransition between a first electrode combination and a second electrodecombination adjacent to the first electrode combination in thepredetermined order by at least incrementally adjusting at least one ofanodic amplitudes assigned to anodes of the first electrode combinationor cathodic amplitudes assigned to cathodes of the first electrodecombination.
 15. The method of claim 1, wherein controlling the medicaldevice to deliver, in the predetermined order, electrical stimulation tothe patient via each electrode combination of the predefined set ofelectrode combinations comprises controlling the medical device todeliver electrical stimulation to the patient according to a predefinedschedule of amplitude adjustments, the predefined schedule including aplurality of steps and, for each step, active electrodes for delivery ofelectrical stimulation therapy, and, for each of the active electrodes,an anodic amplitude setting or a cathodic amplitude setting.
 16. Themethod of claim 15, wherein controlling the medical device according tothe predefined schedule of amplitude adjustments comprises controllingthe medical device to transition between subsequent steps of thepredefined schedule by at least increasing or decreasing at least one ofthe anodic amplitude or the cathodic amplitude for at least one activeelectrode by an amplitude adjustment increment, wherein the amplitudeadjustment increments are substantially the same between subsequentsteps of the predefined schedule.
 17. The method of claim 15, whereincontrolling the medical device according to the predefined schedule ofamplitude adjustments comprises controlling the medical device totransition between subsequent steps of the predefined schedule by atleast increasing or decreasing at least one of the anodic amplitude orthe cathodic amplitude for at least one active electrode by an amplitudeadjustment increment, wherein the predefined schedule includes at leasttwo different amplitude adjustment increments such that controlling themedical device to transition between subsequent steps of the predefinedschedule comprises increasing or decreasing at least one of the anodicamplitude or the cathodic amplitude for at least one active electrode byone amplitude adjustment increment of the at least two differentamplitude adjustment increments.
 18. The method of claim 17, wherein thepredefined schedule includes two different amplitude adjustmentincrements, wherein increasing or decreasing the at least one of theanodic amplitude or the cathodic amplitude for the at least one activeelectrode is by an amplitude adjustment increment of the two differentamplitude adjustment increments that alternates between subsequent stepsof the predefined schedule.
 19. The method of claim 1, whereincontrolling the medical device to deliver, in the predetermined order,electrical stimulation to the patient via each electrode combination ofthe predefined set of electrode combinations comprises controlling themedical device to deliver electrical stimulation to the patient via atleast one electrode combination of the predefined set of electrodecombinations with at least one of a plurality of different anodicamplitude settings or a plurality of different cathodic amplitudesettings.
 20. A system comprising: a medical device a plurality ofelectrodes; and a processor configured to control the medical device todeliver, in a predetermined order, electrical stimulation to a patientvia each electrode combination of a predefined set of electrodecombinations, wherein the electrode combinations of the predefined setof electrode combinations are defined by subsets of electrodes of theplurality of electrodes, and wherein each electrode combination includesone or more anode electrodes, one or more cathode electrodes, or bothone or more anode electrodes and one or more cathode electrodes, arelative arrangement of the one or more anodes and the one or morecathodes defining an electrode pattern of the electrode combination,each pair of adjacent electrode combinations in the predetermined orderincluding at least one same anode electrode or cathode electrode,wherein the electrode combinations in the predetermined order define apredetermined sequence of electrode patterns.
 21. The system of claim20, wherein the processor is configured to select an electrodecombination from the predefined set of electrode combinations based onthe delivery of the electrical stimulation by the medical device. 22.The system of claim 20, wherein at least one electrode pattern appearsmultiple times at different positions in the sequence.
 23. The system ofclaim 20, wherein each pair of adjacent electrode combinations in thepredetermined order include at least one same anode electrode and atleast one same cathode electrode.
 24. The system of claim 20, furthercomprising a memory that stores the predefined set of electrodecombinations in the predetermined order.
 25. The system of claim 20,wherein the medical device comprises the processor.
 26. The system ofclaim 20, further comprising a medical device programmer that comprisesthe processor.
 27. The system of claim 20, wherein the predeterminedsequence of electrode patterns includes a repeating sequence ofelectrode patterns.
 28. The system of claim 20, wherein each patternincludes anodes and cathodes uninterrupted by inactive electrodes. 29.The system of claim 20, further comprising an electrical stimulationlead comprising the plurality of electrodes, the electrode combinationsbeing defined by subsets of electrodes of the plurality of electrodes,wherein the processor is configured to control the medical device todeliver, in the predetermined order, electrical stimulation to thepatient via each electrode combination of the predefined set ofelectrode combinations by at least controlling the medical device todeliver electrical stimulation to the patient via at least two electrodepatterns at two different axial positions along the lead.
 30. The systemof claim 20, further comprising an electrical stimulation leadcomprising the plurality of electrodes, the electrode combinations beingdefined by subsets of electrodes of the plurality of electrodes, whereinthe electrode combinations are arranged in the predetermined order suchthat electrode combinations are transitioned down the lead.
 31. Thesystem of claim 20, further comprising a user interface, wherein theprocessor is configured to receive a first user input via the userinterface, control the medical device to one of pause electricalstimulation or continue delivering electrical stimulation according to acurrently selected electrode combination of the predefined set ofelectrode combinations in response to receiving the first user input,subsequently receive a second user input, and control the medical deviceto transition from the currently selected electrode combination to anext electrode combination in the predetermined order in response toreceiving the second user input.
 32. The system of claim 20, furthercomprising a user interface, wherein the processor is configured toreceive user input selecting a starting electrode via the userinterface, select a starting electrode combination from the predefinedset of electrode combinations based on the starting electrode selectedby the user, and control the medical device to deliver, in thepredetermined order, electrical stimulation to the patient via thestarting electrode combination and each electrode combination of thepredefined set of electrode combinations following the startingelectrode combination in the predetermined order.
 33. The system ofclaim 20, further comprising a user interface, wherein the processor isconfigured to receive user input via the user interface and modify thepredefined set of electrode combinations in response to receiving theuser input.
 34. The system of claim 33, wherein the processor isconfigured to modify the predefined set of electrode combinations by atleast removing at least one electrode combination from the predefinedset of electrode combinations.
 35. The system of claim 20, wherein theelectrode patterns include a first simple bipole, a second simplebipole, a guarded cathode, and a guarded double cathode.
 36. The systemof claim 20, wherein the processor is configured to control the medicaldevice to deliver, in the predetermined order, electrical stimulation tothe patient via each electrode combination of the predefined set ofelectrode combinations by at least controlling the medical device totransition between a first electrode combination and a second electrodecombination adjacent to the first electrode combination in the order byincrementally adjusting at least one of anodic amplitudes assigned toanodes of the first electrode combination or cathodic amplitudesassigned to cathodes of the first electrode combination.
 37. The systemof claim 20, wherein the processor is configured to control the medicaldevice to deliver, in the predetermined order, electrical stimulation tothe patient via each electrode combination of the predefined set ofelectrode combinations in the predetermined order by at leastcontrolling the medical device to deliver electrical stimulation to thepatient according to a predefined schedule of amplitude adjustments, thepredefined schedule including a plurality of steps and, for each step,active electrodes for delivery of electrical stimulation therapy, and,for each of the active electrodes, an anodic amplitude setting or acathodic amplitude setting.
 38. The system of claim 37, wherein theprocessor is configured to control the medical device according to thepredefined schedule of amplitude adjustments by at least controlling themedical device to transition between subsequent steps of the predefinedschedule by at least increasing or decreasing at least one of the anodicamplitude or the cathodic amplitude for at least one active electrode byan amplitude adjustment increment, wherein the amplitude adjustmentincrements are substantially the same between subsequent steps of thepredefined schedule.
 39. The system of claim 37, wherein the processoris configured to control the medical device according to the predefinedschedule of amplitude adjustments by at least controlling the medicaldevice to transition between subsequent steps of the predefined scheduleby at least increasing or decreasing at least one of the anodicamplitude or the cathodic amplitude for at least one active electrode byan amplitude adjustment increment, wherein the predefined scheduleincludes at least two different amplitude adjustment increments suchthat the processor is configured to control the medical device totransition between subsequent steps of the predefined schedule by atleast increasing or decreasing at least one of the anodic amplitude orthe cathodic amplitude for at least one active electrode by oneamplitude adjustment increment of the at least two different amplitudeadjustment increments.
 40. The system of claim 39, wherein thepredefined schedule includes two different amplitude adjustmentincrements, wherein increasing or decreasing the at least one of theanodic amplitude or the cathodic amplitude for the at least one activeelectrode is by an amplitude adjustment increment of the two differentamplitude adjustment increments that alternates between subsequent stepsof the predefined schedule.
 41. The system of claim 20, wherein theprocessor is configured to control the medical device to deliver, in thepredetermined order, electrical stimulation to the patient via eachelectrode combination of the predefined set of electrode combinations byat least controlling the medical device to deliver electricalstimulation to the patient with at least one electrode combination ofthe predefined set of electrode combinations and at least one of aplurality of different anodic amplitude settings or a plurality ofdifferent cathodic amplitude settings.
 42. A system comprising: meansfor delivering electrical stimulation to a patient; and means forcontrolling the means for delivering electrical stimulation to deliver,in a predetermined order, electrical stimulation to the patient via eachelectrode combination of a predefined set of electrode combinations,wherein each electrode combination includes one or more anodeelectrodes, one or more cathode electrodes, or both one or more anodeelectrodes and one or more cathode electrodes, a relative arrangement ofthe one or more anodes and the one or more cathodes defining anelectrode pattern of the electrode combination, each pair of adjacentelectrode combinations in the predetermined order including at least onesame anode electrode or cathode electrode, wherein the electrodecombinations in the predetermined order define a predetermined sequenceof electrode patterns.
 43. The system of claim 42, wherein the electrodepatterns include a first simple bipole, a second simple bipole, aguarded cathode, and a guarded double cathode.
 44. The system of claim42, wherein the means for controlling is configured to control the meansfor delivering electrical stimulation to transition between electrodecombinations of the predefined set of electrode combinations based on apredefined schedule of amplitude adjustments, the predefined scheduleincluding a plurality of steps and, for each step, active electrodes fordelivery of electrical stimulation therapy, and, for each of the activeelectrodes, an anodic amplitude setting or a cathodic amplitude setting.45. A non-transitory computer-readable storage medium comprisinginstructions that, when executed by a processor, cause the processor to:control a medical device to deliver, in a predetermined order,electrical stimulation to a patient via each electrode combination of apredefined set of electrode combinations, wherein each electrodecombination includes one or more anode electrodes, one or more cathodeelectrodes, or both one or more anode electrodes and one or more cathodeelectrodes, a relative arrangement of the one or more anodes and the oneor more cathodes defining an electrode pattern of the electrodecombination, each pair of adjacent electrode combinations in thepredetermined order including at least one same anode electrode orcathode electrode, wherein the electrode combinations in thepredetermined order define a predetermined sequence of electrodepatterns; and select an electrode combination from the predefined set ofelectrode combinations based on the delivery of the electricalstimulation by the medical device.
 46. The non-transitorycomputer-readable storage medium of claim 45, wherein the instructions,when executed by the processor, cause the processor to control themedical device to transition between electrode combinations of thepredefined set of electrode combinations based on a predefined scheduleof amplitude adjustments, the predefined schedule including a pluralityof steps and, for each step, active electrodes for delivery ofelectrical stimulation therapy, and, for each of the active electrodes,an anodic amplitude setting or a cathodic amplitude setting.